# `sqlite3` — DB-API 2.0 interface for SQLite databases

Source code: Lib/sqlite3/

## Introduction

SQLite is a C library that provides a lightweight disk-based database that doesn’t require a separate server process and allows accessing the database using a nonstandard variant of the SQL query language. Some applications can use SQLite for internal data storage. It’s also possible to prototype an application using SQLite and then port the code to a larger database such as PostgreSQL or Oracle.

The sqlite3 module was written by Gerhard Häring. It provides an SQL interface compliant with the DB-API 2.0 specification described by PEP 249, and requires SQLite 3.7.15 or newer.

This document includes four main sections:

- Tutorial teaches how to use the sqlite3 module.

- Reference describes the classes and functions this module defines.

- How-to guides details how to handle specific tasks.

- Explanation provides in-depth background on transaction control.

## Tutorial

To use the module, start by creating a `Connection` object that represents the database. Here the data will be stored in the `example.db` file:

    import sqlite3
    con = sqlite3.connect('example.db')

The special path name `:memory:` can be provided to create a temporary database in RAM.

Once a `Connection` has been established, create a `Cursor` object and call its `execute()` method to perform SQL commands:

    cur = con.cursor()

    # Create table
    cur.execute('''CREATE TABLE stocks
                   (date text, trans text, symbol text, qty real, price real)''')

    # Insert a row of data
    cur.execute("INSERT INTO stocks VALUES ('2006-01-05','BUY','RHAT',100,35.14)")

    # Save (commit) the changes
    con.commit()

    # We can also close the connection if we are done with it.
    # Just be sure any changes have been committed or they will be lost.
    con.close()

The saved data is persistent: it can be reloaded in a subsequent session even after restarting the Python interpreter:

    import sqlite3
    con = sqlite3.connect('example.db')
    cur = con.cursor()

At this point, our database only contains one row:

    >>> res = cur.execute('SELECT count(rowid) FROM stocks')
    >>> print(res.fetchone())
    (1,)

The result is a one-item `tuple`: one row, with one column. Now, let us insert three more rows of data, using `executemany()`:

    >>> data = [
    ...    ('2006-03-28', 'BUY', 'IBM', 1000, 45.0),
    ...    ('2006-04-05', 'BUY', 'MSFT', 1000, 72.0),
    ...    ('2006-04-06', 'SELL', 'IBM', 500, 53.0),
    ... ]
    >>> cur.executemany('INSERT INTO stocks VALUES(?, ?, ?, ?, ?)', data)

Notice that we used `?` placeholders to bind data to the query. Always use placeholders instead of string formatting to bind Python values to SQL statements, to avoid SQL injection attacks. See the placeholders how-to for more details.

Then, retrieve the data by iterating over the result of a `SELECT` statement:

    >>> for row in cur.execute('SELECT * FROM stocks ORDER BY price'):
    ...     print(row)

    ('2006-01-05', 'BUY', 'RHAT', 100, 35.14)
    ('2006-03-28', 'BUY', 'IBM', 1000, 45.0)
    ('2006-04-06', 'SELL', 'IBM', 500, 53.0)
    ('2006-04-05', 'BUY', 'MSFT', 1000, 72.0)

You’ve now created an SQLite database using the `sqlite3` module.

See also

https://www.sqlite.org

  The SQLite web page; the documentation describes the syntax and the available data types for the supported SQL dialect.

https://www.w3schools.com/sql/

  Tutorial, reference and examples for learning SQL syntax.

PEP 249 - Database API Specification 2.0

  PEP written by Marc-André Lemburg.

## Reference

### Module functions and constants

sqlite3.apilevel

  String constant stating the supported DB-API level. Required by the DB-API. Hard-coded to `"2.0"`.

sqlite3.paramstyle

  String constant stating the type of parameter marker formatting expected by the `sqlite3` module. Required by the DB-API. Hard-coded to `"qmark"`.

  Note

  The `sqlite3` module supports both `qmark` and `numeric` DB-API parameter styles, because that is what the underlying SQLite library supports. However, the DB-API does not allow multiple values for the `paramstyle` attribute.

sqlite3.version

  Version number of this module as a `string`. This is not the version of the SQLite library.

sqlite3.version_info

  Version number of this module as a `tuple` of `integers`. This is not the version of the SQLite library.

sqlite3.sqlite_version

  Version number of the runtime SQLite library as a `string`.

sqlite3.sqlite_version_info

  Version number of the runtime SQLite library as a `tuple` of `integers`.

sqlite3.threadsafety

  Integer constant required by the DB-API 2.0, stating the level of thread safety the `sqlite3` module supports. This attribute is set based on the default threading mode the underlying SQLite library is compiled with. The SQLite threading modes are:

  > 1. Single-thread: In this mode, all mutexes are disabled and SQLite is unsafe to use in more than a single thread at once.

  > 2. Multi-thread: In this mode, SQLite can be safely used by multiple threads provided that no single database connection is used simultaneously in two or more threads.

  > 3. Serialized: In serialized mode, SQLite can be safely used by multiple threads with no restriction.

  The mappings from SQLite threading modes to DB-API 2.0 threadsafety levels are as follows:

  SQLite threading mode | threadsafety | SQLITE_THREADSAFE | DB-API 2.0 meaning
  --- | --- | --- | ---
  single-thread | 0 | 0 | Threads may not share the module
  multi-thread | 1 | 2 | Threads may share the module, but not connections
  serialized | 3 | 1 | Threads may share the module, connections and cursors

  Changed in version 3.11: Set threadsafety dynamically instead of hard-coding it to `1`.

sqlite3.PARSE_DECLTYPES

  Pass this flag value to the detect_types parameter of `connect()` to look up a converter function using the declared types for each column. The types are declared when the database table is created. `sqlite3` will look up a converter function using the first word of the declared type as the converter dictionary key. For example:

      CREATE TABLE test(
         i integer primary key,  ! will look up a converter named "integer"
         p point,                ! will look up a converter named "point"
         n number(10)            ! will look up a converter named "number"
       )

  This flag may be combined with `PARSE_COLNAMES` using the `|` (bitwise or) operator.

sqlite3.PARSE_COLNAMES

  Pass this flag value to the detect_types parameter of `connect()` to look up a converter function by using the type name, parsed from the query column name, as the converter dictionary key. The type name must be wrapped in square brackets (`[]`).

      SELECT p as "p [point]" FROM test;  ! will look up converter "point"

  This flag may be combined with `PARSE_DECLTYPES` using the `|` (bitwise or) operator.

sqlite3.connect(database, timeout=5.0, detect_types=0, isolation_level='DEFERRED', check_same_thread=True, factory=sqlite3.Connection, cached_statements=128, uri=False)

  Open a connection to an SQLite database.

  Parameters

    - database (path-like object) – The path to the database file to be opened. Pass `":memory:"` to open a connection to a database that is in RAM instead of on disk.

    - timeout (float) – How many seconds the connection should wait before raising an exception, if the database is locked by another connection. If another connection opens a transaction to modify the database, it will be locked until that transaction is committed. Default five seconds.

    - detect_types (int) – Control whether and how data types not natively supported by SQLite are looked up to be converted to Python types, using the converters registered with `register_converter()`. Set it to any combination (using `|`, bitwise or) of `PARSE_DECLTYPES` and `PARSE_COLNAMES` to enable this. Column names takes precedence over declared types if both flags are set. Types cannot be detected for generated fields (for example `max(data)`), even when the detect_types parameter is set; `str` will be returned instead. By default (`0`), type detection is disabled.

    - isolation_level (str | None) – The `isolation_level` of the connection, controlling whether and how transactions are implicitly opened. Can be `"DEFERRED"` (default), `"EXCLUSIVE"` or `"IMMEDIATE"`; or `None` to disable opening transactions implicitly. See Transaction control for more.

    - check_same_thread (bool) – If `True` (default), only the creating thread may use the connection. If `False`, the connection may be shared across multiple threads; if so, write operations should be serialized by the user to avoid data corruption.

    - factory (Connection) – A custom subclass of `Connection` to create the connection with, if not the default `Connection` class.

    - cached_statements (int) – The number of statements that `sqlite3` should internally cache for this connection, to avoid parsing overhead. By default, 128 statements.

    - uri (bool) – If set to `True`, database is interpreted as a URI with a file path and an optional query string. The scheme part must be `"file:"`, and the path can be relative or absolute. The query string allows passing parameters to SQLite, enabling various Working with SQLite URIs.

  Return type

    Connection

  Raises an auditing event `sqlite3.connect` with argument `database`.

  Raises an auditing event `sqlite3.connect/handle` with argument `connection_handle`.

  New in version 3.4: The uri parameter.

  Changed in version 3.7: database can now also be a path-like object, not only a string.

  New in version 3.10: The `sqlite3.connect/handle` auditing event.

sqlite3.register_converter(typename, converter, /)

  Register the converter callable to convert SQLite objects of type typename into a Python object of a specific type. The converter is invoked for all SQLite values of type typename; it is passed a `bytes` object and should return an object of the desired Python type. Consult the parameter detect_types of `connect()` for information regarding how type detection works.

  Note: typename and the name of the type in your query are matched case-insensitively.

sqlite3.register_adapter(type, adapter, /)

  Register an adapter callable to adapt the Python type type into an SQLite type. The adapter is called with a Python object of type type as its sole argument, and must return a value of a type that SQLite natively understands.

sqlite3.complete_statement(statement)

  Returns `True` if the string statement contains one or more complete SQL statements terminated by semicolons. It does not verify that the SQL is syntactically correct, only that there are no unclosed string literals and the statement is terminated by a semicolon.

  This can be used to build a shell for SQLite, as in the following example:

      # A minimal SQLite shell for experiments

      import sqlite3

      con = sqlite3.connect(":memory:")
      con.isolation_level = None
      cur = con.cursor()

      buffer = ""

      print("Enter your SQL commands to execute in sqlite3.")
      print("Enter a blank line to exit.")

      while True:
          line = input()
          if line == "":
              break
          buffer += line
          if sqlite3.complete_statement(buffer):
              try:
                  buffer = buffer.strip()
                  cur.execute(buffer)

                  if buffer.lstrip().upper().startswith("SELECT"):
                      print(cur.fetchall())
              except sqlite3.Error as e:
                  err_msg = str(e)
                  err_code = e.sqlite_errorcode
                  err_name = e.sqlite_errorname
                  print(f"{err_name} ({err_code}): {err_msg}")
              buffer = ""

      con.close()

sqlite3.enable_callback_tracebacks(flag, /)

  Enable or disable callback tracebacks. By default you will not get any tracebacks in user-defined functions, aggregates, converters, authorizer callbacks etc. If you want to debug them, you can call this function with flag set to `True`. Afterwards, you will get tracebacks from callbacks on `sys.stderr`. Use `False` to disable the feature again.

  Register an `unraisable hook handler` for an improved debug experience:

      >>> import sqlite3
      >>> sqlite3.enable_callback_tracebacks(True)
      >>> cx = sqlite3.connect(":memory:")
      >>> cx.set_trace_callback(lambda stmt: 5/0)
      >>> cx.execute("select 1")
      Exception ignored in: <function <lambda> at 0x10b4e3ee0>
      Traceback (most recent call last):
        File "<stdin>", line 1, in <lambda>
      ZeroDivisionError: division by zero
      >>> import sys
      >>> sys.unraisablehook = lambda unraisable: print(unraisable)
      >>> cx.execute("select 1")
      UnraisableHookArgs(exc_type=<class 'ZeroDivisionError'>, exc_value=ZeroDivisionError('division by zero'), exc_traceback=<traceback object at 0x10b559900>, err_msg=None, object=<function <lambda> at 0x10b4e3ee0>)
      <sqlite3.Cursor object at 0x10b1fe840>

### Connection objects

class sqlite3.Connection

  Each open SQLite database is represented by a `Connection` object, which is created using `sqlite3.connect()`. Their main purpose is creating `Cursor` objects, and Transaction control.

  See also

  - Using connection shortcut methods

  - Using the connection as a context manager

  An SQLite database connection has the following attributes and methods:

  isolation_level

    This attribute controls the transaction handling performed by `sqlite3`. If set to `None`, transactions are never implicitly opened. If set to one of `"DEFERRED"`, `"IMMEDIATE"`, or `"EXCLUSIVE"`, corresponding to the underlying SQLite transaction behaviour, implicit transaction management is performed.

    If not overridden by the isolation_level parameter of `connect()`, the default is `""`, which is an alias for `"DEFERRED"`.

  in_transaction

    This read-only attribute corresponds to the low-level SQLite autocommit mode.

    `True` if a transaction is active (there are uncommitted changes), `False` otherwise.

    New in version 3.2.

  cursor(factory=Cursor)

    Create and return a `Cursor` object. The cursor method accepts a single optional parameter factory. If supplied, this must be a callable returning an instance of `Cursor` or its subclasses.

  blobopen(table, column, row, /, *, readonly=False, name='main')

    Open a `Blob` handle to an existing BLOB.

    Parameters

      - table (str) – The name of the table where the blob is located.

      - column (str) – The name of the column where the blob is located.

      - row (str) – The name of the row where the blob is located.

      - readonly (bool) – Set to `True` if the blob should be opened without write permissions. Defaults to `False`.

      - name (str) – The name of the database where the blob is located. Defaults to `"main"`.

    Raises

      OperationalError – When trying to open a blob in a `WITHOUT ROWID` table.

    Return type

      Blob

    Note

    The blob size cannot be changed using the `Blob` class. Use the SQL function `zeroblob` to create a blob with a fixed size.

    New in version 3.11.

  commit()

    Commit any pending transaction to the database. If there is no open transaction, this method is a no-op.

  rollback()

    Roll back to the start of any pending transaction. If there is no open transaction, this method is a no-op.

  close()

    Close the database connection. Any pending transaction is not committed implicitly; make sure to `commit()` before closing to avoid losing pending changes.

  execute(sql, parameters=(), /)

    Create a new `Cursor` object and call `execute()` on it with the given sql and parameters. Return the new cursor object.

  executemany(sql, parameters, /)

    Create a new `Cursor` object and call `executemany()` on it with the given sql and parameters. Return the new cursor object.

  executescript(sql_script, /)

    Create a new `Cursor` object and call `executescript()` on it with the given sql_script. Return the new cursor object.

  create_function(name, narg, func, *, deterministic=False)

    Create or remove a user-defined SQL function.

    Parameters

      - name (str) – The name of the SQL function.

      - narg (int) – The number of arguments the SQL function can accept. If `-1`, it may take any number of arguments.

      - func (callback | None) – A callable that is called when the SQL function is invoked. The callable must return a type natively supported by SQLite. Set to `None` to remove an existing SQL function.

      - deterministic (bool) – If `True`, the created SQL function is marked as deterministic, which allows SQLite to perform additional optimizations.

    Raises

      NotSupportedError – If deterministic is used with SQLite versions older than 3.8.3.

    New in version 3.8: The deterministic parameter.

    Example:

        import sqlite3
        import hashlib

        def md5sum(t):
            return hashlib.md5(t).hexdigest()

        con = sqlite3.connect(":memory:")
        con.create_function("md5", 1, md5sum)
        cur = con.cursor()
        cur.execute("select md5(?)", (b"foo",))
        print(cur.fetchone()[0])

        con.close()

  create_aggregate(name, /, n_arg, aggregate_class)

    Create or remove a user-defined SQL aggregate function.

    Parameters

      - name (str) – The name of the SQL aggregate function.

      - n_arg (int) – The number of arguments the SQL aggregate function can accept. If `-1`, it may take any number of arguments.

      - aggregate_class (class | None) –

        A class must implement the following methods:

        - `step()`: Add a row to the aggregate.

        - `finalize()`: Return the final result of the aggregate as a type natively supported by SQLite.

        The number of arguments that the `step()` method must accept is controlled by n_arg.

        Set to `None` to remove an existing SQL aggregate function.

    Example:

        import sqlite3

        class MySum:
            def __init__(self):
                self.count = 0

            def step(self, value):
                self.count += value

            def finalize(self):
                return self.count

        con = sqlite3.connect(":memory:")
        con.create_aggregate("mysum", 1, MySum)
        cur = con.cursor()
        cur.execute("create table test(i)")
        cur.execute("insert into test(i) values (1)")
        cur.execute("insert into test(i) values (2)")
        cur.execute("select mysum(i) from test")
        print(cur.fetchone()[0])

        con.close()

  create_window_function(name, num_params, aggregate_class, /)

    Create or remove a user-defined aggregate window function.

    Parameters

      - name (str) – The name of the SQL aggregate window function to create or remove.

      - num_params (int) – The number of arguments the SQL aggregate window function can accept. If `-1`, it may take any number of arguments.

      - aggregate_class (class | None) –

        A class that must implement the following methods:

        - `step()`: Add a row to the current window.

        - `value()`: Return the current value of the aggregate.

        - `inverse()`: Remove a row from the current window.

        - `finalize()`: Return the final result of the aggregate as a type natively supported by SQLite.

        The number of arguments that the `step()` and `value()` methods must accept is controlled by num_params.

        Set to `None` to remove an existing SQL aggregate window function.

    Raises

      NotSupportedError – If used with a version of SQLite older than 3.25.0, which does not support aggregate window functions.

    New in version 3.11.

    Example:

        # Example taken from https://www.sqlite.org/windowfunctions.html#udfwinfunc
        import sqlite3

        class WindowSumInt:
            def __init__(self):
                self.count = 0

            def step(self, value):
                """Adds a row to the current window."""
                self.count += value

            def value(self):
                """Returns the current value of the aggregate."""
                return self.count

            def inverse(self, value):
                """Removes a row from the current window."""
                self.count -= value

            def finalize(self):
                """Returns the final value of the aggregate.

                Any clean-up actions should be placed here.
                """
                return self.count

        con = sqlite3.connect(":memory:")
        cur = con.execute("create table test(x, y)")
        values = [
            ("a", 4),
            ("b", 5),
            ("c", 3),
            ("d", 8),
            ("e", 1),
        ]
        cur.executemany("insert into test values(?, ?)", values)
        con.create_window_function("sumint", 1, WindowSumInt)
        cur.execute("""
            select x, sumint(y) over (
                order by x rows between 1 preceding and 1 following
            ) as sum_y
            from test order by x
        """)
        print(cur.fetchall())

  create_collation(name, callable)

    Create a collation named name using the collating function callable. callable is passed two `string` arguments, and it should return an `integer`:

    - `1` if the first is ordered higher than the second

    - `-1` if the first is ordered lower than the second

    - `0` if they are ordered equal

    The following example shows a reverse sorting collation:

        import sqlite3

        def collate_reverse(string1, string2):
            if string1 == string2:
                return 0
            elif string1 < string2:
                return 1
            else:
                return -1

        con = sqlite3.connect(":memory:")
        con.create_collation("reverse", collate_reverse)

        cur = con.cursor()
        cur.execute("create table test(x)")
        cur.executemany("insert into test(x) values (?)", [("a",), ("b",)])
        cur.execute("select x from test order by x collate reverse")
        for row in cur:
            print(row)
        con.close()

    Remove a collation function by setting callable to `None`.

    Changed in version 3.11: The collation name can contain any Unicode character. Earlier, only ASCII characters were allowed.

  interrupt()

    Call this method from a different thread to abort any queries that might be executing on the connection. Aborted queries will raise an exception.

  set_authorizer(authorizer_callback)

    Register callable authorizer_callback to be invoked for each attempt to access a column of a table in the database. The callback should return `SQLITE_OK` if access is allowed, `SQLITE_DENY` if the entire SQL statement should be aborted with an error and `SQLITE_IGNORE` if the column should be treated as a NULL value. These constants are available in the `sqlite3` module.

    The first argument to the callback signifies what kind of operation is to be authorized. The second and third argument will be arguments or `None` depending on the first argument. The 4th argument is the name of the database (“main”, “temp”, etc.) if applicable. The 5th argument is the name of the inner-most trigger or view that is responsible for the access attempt or `None` if this access attempt is directly from input SQL code.

    Please consult the SQLite documentation about the possible values for the first argument and the meaning of the second and third argument depending on the first one. All necessary constants are available in the `sqlite3` module.

    Passing `None` as authorizer_callback will disable the authorizer.

    Changed in version 3.11: Added support for disabling the authorizer using `None`.

  set_progress_handler(progress_handler, n)

    Register callable progress_handler to be invoked for every n instructions of the SQLite virtual machine. This is useful if you want to get called from SQLite during long-running operations, for example to update a GUI.

    If you want to clear any previously installed progress handler, call the method with `None` for progress_handler.

    Returning a non-zero value from the handler function will terminate the currently executing query and cause it to raise an `OperationalError` exception.

  set_trace_callback(trace_callback)

    Register callable trace_callback to be invoked for each SQL statement that is actually executed by the SQLite backend.

    The only argument passed to the callback is the statement (as `str`) that is being executed. The return value of the callback is ignored. Note that the backend does not only run statements passed to the `Cursor.execute()` methods. Other sources include the transaction management of the sqlite3 module and the execution of triggers defined in the current database.

    Passing `None` as trace_callback will disable the trace callback.

    Note

    Exceptions raised in the trace callback are not propagated. As a development and debugging aid, use `enable_callback_tracebacks()` to enable printing tracebacks from exceptions raised in the trace callback.

    New in version 3.3.

  enable_load_extension(enabled, /)

    Enable the SQLite engine to load SQLite extensions from shared libraries if enabled is `True`; else, disallow loading SQLite extensions. SQLite extensions can define new functions, aggregates or whole new virtual table implementations. One well-known extension is the fulltext-search extension distributed with SQLite.

    Note

    The `sqlite3` module is not built with loadable extension support by default, because some platforms (notably macOS) have SQLite libraries which are compiled without this feature. To get loadable extension support, you must pass the `--enable-loadable-sqlite-extensions` option to configure.

    Raises an auditing event `sqlite3.enable_load_extension` with arguments `connection`, `enabled`.

    New in version 3.2.

    Changed in version 3.10: Added the `sqlite3.enable_load_extension` auditing event.

        import sqlite3

        con = sqlite3.connect(":memory:")

        # enable extension loading
        con.enable_load_extension(True)

        # Load the fulltext search extension
        con.execute("select load_extension('./fts3.so')")

        # alternatively you can load the extension using an API call:
        # con.load_extension("./fts3.so")

        # disable extension loading again
        con.enable_load_extension(False)

        # example from SQLite wiki
        con.execute("create virtual table recipe using fts3(name, ingredients)")
        con.executescript("""
            insert into recipe (name, ingredients) values ('broccoli stew', 'broccoli peppers cheese tomatoes');
            insert into recipe (name, ingredients) values ('pumpkin stew', 'pumpkin onions garlic celery');
            insert into recipe (name, ingredients) values ('broccoli pie', 'broccoli cheese onions flour');
            insert into recipe (name, ingredients) values ('pumpkin pie', 'pumpkin sugar flour butter');
            """)
        for row in con.execute("select rowid, name, ingredients from recipe where name match 'pie'"):
            print(row)

        con.close()

  load_extension(path, /)

    Load an SQLite extension from a shared library located at path. Enable extension loading with `enable_load_extension()` before calling this method.

    Raises an auditing event `sqlite3.load_extension` with arguments `connection`, `path`.

    New in version 3.2.

    Changed in version 3.10: Added the `sqlite3.load_extension` auditing event.

  row_factory

    A callable that accepts two arguments, a `Cursor` object and the raw row results as a `tuple`, and returns a custom object representing an SQLite row.

    Example:

        import sqlite3

        def dict_factory(cursor, row):
            d = {}
            for idx, col in enumerate(cursor.description):
                d[col[0]] = row[idx]
            return d

        con = sqlite3.connect(":memory:")
        con.row_factory = dict_factory
        cur = con.cursor()
        cur.execute("select 1 as a")
        print(cur.fetchone()["a"])

        con.close()

    If returning a tuple doesn’t suffice and you want name-based access to columns, you should consider setting `row_factory` to the highly optimized `sqlite3.Row` type. `Row` provides both index-based and case-insensitive name-based access to columns with almost no memory overhead. It will probably be better than your own custom dictionary-based approach or even a db_row based solution.

  text_factory

    A callable that accepts a `bytes` parameter and returns a text representation of it. The callable is invoked for SQLite values with the `TEXT` data type. By default, this attribute is set to `str`. If you want to return `bytes` instead, set text_factory to `bytes`.

    Example:

        import sqlite3

        con = sqlite3.connect(":memory:")
        cur = con.cursor()

        AUSTRIA = "Österreich"

        # by default, rows are returned as str
        cur.execute("select ?", (AUSTRIA,))
        row = cur.fetchone()
        assert row[0] == AUSTRIA

        # but we can make sqlite3 always return bytestrings ...
        con.text_factory = bytes
        cur.execute("select ?", (AUSTRIA,))
        row = cur.fetchone()
        assert type(row[0]) is bytes
        # the bytestrings will be encoded in UTF-8, unless you stored garbage in the
        # database ...
        assert row[0] == AUSTRIA.encode("utf-8")

        # we can also implement a custom text_factory ...
        # here we implement one that appends "foo" to all strings
        con.text_factory = lambda x: x.decode("utf-8") + "foo"
        cur.execute("select ?", ("bar",))
        row = cur.fetchone()
        assert row[0] == "barfoo"

        con.close()

  total_changes

    Return the total number of database rows that have been modified, inserted, or deleted since the database connection was opened.

  iterdump()

    Return an iterator to dump the database as SQL source code. Useful when saving an in-memory database for later restoration. Similar to the `.dump` command in the sqlite3 shell.

    Example:

        # Convert file existing_db.db to SQL dump file dump.sql
        import sqlite3

        con = sqlite3.connect('existing_db.db')
        with open('dump.sql', 'w') as f:
            for line in con.iterdump():
                f.write('%s\n' % line)
        con.close()

  backup(target, *, pages=- 1, progress=None, name='main', sleep=0.250)

    Create a backup of an SQLite database.

    Works even if the database is being accessed by other clients or concurrently by the same connection.

    Parameters

      - target (Connection) – The database connection to save the backup to.

      - pages (int) – The number of pages to copy at a time. If equal to or less than `0`, the entire database is copied in a single step. Defaults to `-1`.

      - progress (callback | None) – If set to a callable, it is invoked with three integer arguments for every backup iteration: the status of the last iteration, the remaining number of pages still to be copied, and the total number of pages. Defaults to `None`.

      - name (str) – The name of the database to back up. Either `"main"` (the default) for the main database, `"temp"` for the temporary database, or the name of a custom database as attached using the `ATTACH DATABASE` SQL statement.

      - sleep (float) – The number of seconds to sleep between successive attempts to back up remaining pages.

    Example 1, copy an existing database into another:

        import sqlite3

        def progress(status, remaining, total):
            print(f'Copied {total-remaining} of {total} pages...')

        con = sqlite3.connect('existing_db.db')
        bck = sqlite3.connect('backup.db')
        with bck:
            con.backup(bck, pages=1, progress=progress)
        bck.close()
        con.close()

    Example 2, copy an existing database into a transient copy:

        import sqlite3

        source = sqlite3.connect('existing_db.db')
        dest = sqlite3.connect(':memory:')
        source.backup(dest)

    New in version 3.7.

  getlimit(category, /)

    Get a connection runtime limit.

    Parameters

      category (int) – The SQLite limit category to be queried.

    Return type

      int

    Raises

      ProgrammingError – If category is not recognised by the underlying SQLite library.

    Example, query the maximum length of an SQL statement:

        import sqlite3
        con = sqlite3.connect(":memory:")
        lim = con.getlimit(sqlite3.SQLITE_LIMIT_SQL_LENGTH)
        print(f"SQLITE_LIMIT_SQL_LENGTH={lim}")

    New in version 3.11.

  setlimit(category, limit, /)

    Set a connection runtime limit. Attempts to increase a limit above its hard upper bound are silently truncated to the hard upper bound. Regardless of whether or not the limit was changed, the prior value of the limit is returned.

    Parameters

      - category (int) – The SQLite limit category to be set.

      - limit (int) – The value of the new limit. If negative, the current limit is unchanged.

    Return type

      int

    Raises

      ProgrammingError – If category is not recognised by the underlying SQLite library.

    Example, limit the number of attached databases to 1:

        import sqlite3
        con = sqlite3.connect(":memory:")
        con.setlimit(sqlite3.SQLITE_LIMIT_ATTACHED, 1)

    New in version 3.11.

  serialize(*, name='main')

    Serialize a database into a `bytes` object. For an ordinary on-disk database file, the serialization is just a copy of the disk file. For an in-memory database or a “temp” database, the serialization is the same sequence of bytes which would be written to disk if that database were backed up to disk.

    Parameters

      name (str) – The database name to be serialized. Defaults to `"main"`.

    Return type

      bytes

    Note

    This method is only available if the underlying SQLite library has the serialize API.

    New in version 3.11.

  deserialize(data, /, *, name='main')

    Deserialize a `serialized` database into a `Connection`. This method causes the database connection to disconnect from database name, and reopen name as an in-memory database based on the serialization contained in data.

    Parameters

      - data (bytes) – A serialized database.

      - name (str) – The database name to deserialize into. Defaults to `"main"`.

    Raises

      - OperationalError – If the database connection is currently involved in a read transaction or a backup operation.

      - DatabaseError – If data does not contain a valid SQLite database.

      - OverflowError – If `len(data)` is larger than `2**63 - 1`.

    Note

    This method is only available if the underlying SQLite library has the deserialize API.

    New in version 3.11.

### Cursor objects

> A `Cursor` object represents a database cursor which is used to execute SQL statements, and manage the context of a fetch operation. Cursors are created using `Connection.cursor()`, or by using any of the connection shortcut methods.

> Cursor objects are iterators, meaning that if you `execute()` a `SELECT` query, you can simply iterate over the cursor to fetch the resulting rows:

>     for row in cur.execute("select * from data"):
>         print(row)

class sqlite3.Cursor

  A `Cursor` instance has the following attributes and methods.

  execute(sql, parameters=(), /)

    Execute SQL statement sql. Bind values to the statement using placeholders that map to the sequence or `dict` parameters.

    `execute()` will only execute a single SQL statement. If you try to execute more than one statement with it, it will raise a `ProgrammingError`. Use `executescript()` if you want to execute multiple SQL statements with one call.

    If `isolation_level` is not `None`, sql is an `INSERT`, `UPDATE`, `DELETE`, or `REPLACE` statement, and there is no open transaction, a transaction is implicitly opened before executing sql.

  executemany(sql, parameters, /)

    Execute parameterized SQL statement sql against all parameter sequences or mappings found in the sequence parameters. It is also possible to use an iterator yielding parameters instead of a sequence. Uses the same implicit transaction handling as `execute()`.

    Example:

        data = [
            ("row1",),
            ("row2",),
        ]
        # cur is an sqlite3.Cursor object
        cur.executemany("insert into t values(?)", data)

  executescript(sql_script, /)

    Execute the SQL statements in sql_script. If there is a pending transaction, an implicit `COMMIT` statement is executed first. No other implicit transaction control is performed; any transaction control must be added to sql_script.

    sql_script must be a `string`.

    Example:

        # cur is an sqlite3.Cursor object
        cur.executescript("""
            begin;
            create table person(firstname, lastname, age);
            create table book(title, author, published);
            create table publisher(name, address);
            commit;
        """)

  fetchone()

    Return the next row of a query result set as a `tuple`. Return `None` if no more data is available.

  fetchmany(size=cursor.arraysize)

    Return the next set of rows of a query result as a `list`. Return an empty list if no more rows are available.

    The number of rows to fetch per call is specified by the size parameter. If size is not given, `arraysize` determines the number of rows to be fetched. If fewer than size rows are available, as many rows as are available are returned.

    Note there are performance considerations involved with the size parameter. For optimal performance, it is usually best to use the arraysize attribute. If the size parameter is used, then it is best for it to retain the same value from one `fetchmany()` call to the next.

  fetchall()

    Return all (remaining) rows of a query result as a `list`. Return an empty list if no rows are available. Note that the `arraysize` attribute can affect the performance of this operation.

  close()

    Close the cursor now (rather than whenever `__del__` is called).

    The cursor will be unusable from this point forward; a `ProgrammingError` exception will be raised if any operation is attempted with the cursor.

  setinputsizes(sizes, /)

    Required by the DB-API. Does nothing in `sqlite3`.

  setoutputsize(size, column=None, /)

    Required by the DB-API. Does nothing in `sqlite3`.

  rowcount

    Read-only attribute that provides the number of modified rows for `INSERT`, `UPDATE`, `DELETE`, and `REPLACE` statements; is `-1` for other statements, including CTE queries. It is only updated by the `execute()` and `executemany()` methods.

  lastrowid

    Read-only attribute that provides the row id of the last inserted row. It is only updated after successful `INSERT` or `REPLACE` statements using the `execute()` method. For other statements, after `executemany()` or `executescript()`, or if the insertion failed, the value of `lastrowid` is left unchanged. The initial value of `lastrowid` is `None`.

    Note

    Inserts into `WITHOUT ROWID` tables are not recorded.

    Changed in version 3.6: Added support for the `REPLACE` statement.

  arraysize

    Read/write attribute that controls the number of rows returned by `fetchmany()`. The default value is 1 which means a single row would be fetched per call.

  description

    Read-only attribute that provides the column names of the last query. To remain compatible with the Python DB API, it returns a 7-tuple for each column where the last six items of each tuple are `None`.

    It is set for `SELECT` statements without any matching rows as well.

  connection

    Read-only attribute that provides the SQLite database `Connection` belonging to the cursor. A `Cursor` object created by calling `con.cursor()` will have a `connection` attribute that refers to con:

        >>> con = sqlite3.connect(":memory:")
        >>> cur = con.cursor()
        >>> cur.connection == con
        True

### Row objects

class sqlite3.Row

  A `Row` instance serves as a highly optimized `row_factory` for `Connection` objects. It tries to mimic a `tuple` in most of its features, and supports iteration, `repr()`, equality testing, `len()`, and mapping access by column name and index.

  Two row objects compare equal if have equal columns and equal members.

  keys()

    Return a `list` of column names as `strings`. Immediately after a query, it is the first member of each tuple in `Cursor.description`.

  Changed in version 3.5: Added support of slicing.

Let’s assume we initialize a table as in the example given above:

    con = sqlite3.connect(":memory:")
    cur = con.cursor()
    cur.execute('''create table stocks
    (date text, trans text, symbol text,
     qty real, price real)''')
    cur.execute("""insert into stocks
                values ('2006-01-05','BUY','RHAT',100,35.14)""")
    con.commit()
    cur.close()

Now we plug `Row` in:

    >>> con.row_factory = sqlite3.Row
    >>> cur = con.cursor()
    >>> cur.execute('select * from stocks')
    <sqlite3.Cursor object at 0x7f4e7dd8fa80>
    >>> r = cur.fetchone()
    >>> type(r)
    <class 'sqlite3.Row'>
    >>> tuple(r)
    ('2006-01-05', 'BUY', 'RHAT', 100.0, 35.14)
    >>> len(r)
    5
    >>> r[2]
    'RHAT'
    >>> r.keys()
    ['date', 'trans', 'symbol', 'qty', 'price']
    >>> r['qty']
    100.0
    >>> for member in r:
    ...     print(member)
    ...
    2006-01-05
    BUY
    RHAT
    100.0
    35.14

### Blob objects

New in version 3.11.

class sqlite3.Blob

  A `Blob` instance is a file-like object that can read and write data in an SQLite BLOB. Call `len(blob)` to get the size (number of bytes) of the blob. Use indices and slices for direct access to the blob data.

  Use the `Blob` as a context manager to ensure that the blob handle is closed after use.

      import sqlite3

      con = sqlite3.connect(":memory:")
      con.execute("create table test(blob_col blob)")
      con.execute("insert into test(blob_col) values (zeroblob(13))")

      # Write to our blob, using two write operations:
      with con.blobopen("test", "blob_col", 1) as blob:
          blob.write(b"hello, ")
          blob.write(b"world.")
          # Modify the first and last bytes of our blob
          blob[0] = ord("H")
          blob[-1] = ord("!")

      # Read the contents of our blob
      with con.blobopen("test", "blob_col", 1) as blob:
          greeting = blob.read()

      print(greeting)  # outputs "b'Hello, world!'"

  close()

    Close the blob.

    The blob will be unusable from this point onward. An `Error` (or subclass) exception will be raised if any further operation is attempted with the blob.

  read(length=- 1, /)

    Read length bytes of data from the blob at the current offset position. If the end of the blob is reached, the data up to EOF will be returned. When length is not specified, or is negative, `read()` will read until the end of the blob.

  write(data, /)

    Write data to the blob at the current offset. This function cannot change the blob length. Writing beyond the end of the blob will raise `ValueError`.

  tell()

    Return the current access position of the blob.

  seek(offset, origin=os.SEEK_SET, /)

    Set the current access position of the blob to offset. The origin argument defaults to `os.SEEK_SET` (absolute blob positioning). Other values for origin are `os.SEEK_CUR` (seek relative to the current position) and `os.SEEK_END` (seek relative to the blob’s end).

### PrepareProtocol objects

class sqlite3.PrepareProtocol

  The PrepareProtocol type’s single purpose is to act as a PEP 246 style adaption protocol for objects that can adapt themselves to native SQLite types.

### Exceptions

The exception hierarchy is defined by the DB-API 2.0 (PEP 249).

exception sqlite3.Warning

  This exception is not currently raised by the `sqlite3` module, but may be raised by applications using `sqlite3`, for example if a user-defined function truncates data while inserting. `Warning` is a subclass of `Exception`.

exception sqlite3.Error

  The base class of the other exceptions in this module. Use this to catch all errors with one single `except` statement. `Error` is a subclass of `Exception`.

  If the exception originated from within the SQLite library, the following two attributes are added to the exception:

  sqlite_errorcode

    The numeric error code from the SQLite API

    New in version 3.11.

  sqlite_errorname

    The symbolic name of the numeric error code from the SQLite API

    New in version 3.11.

exception sqlite3.InterfaceError

  Exception raised for misuse of the low-level SQLite C API. In other words, if this exception is raised, it probably indicates a bug in the `sqlite3` module. `InterfaceError` is a subclass of `Error`.

exception sqlite3.DatabaseError

  Exception raised for errors that are related to the database. This serves as the base exception for several types of database errors. It is only raised implicitly through the specialised subclasses. `DatabaseError` is a subclass of `Error`.

exception sqlite3.DataError

  Exception raised for errors caused by problems with the processed data, like numeric values out of range, and strings which are too long. `DataError` is a subclass of `DatabaseError`.

exception sqlite3.OperationalError

  Exception raised for errors that are related to the database’s operation, and not necessarily under the control of the programmer. For example, the database path is not found, or a transaction could not be processed. `OperationalError` is a subclass of `DatabaseError`.

exception sqlite3.IntegrityError

  Exception raised when the relational integrity of the database is affected, e.g. a foreign key check fails. It is a subclass of `DatabaseError`.

exception sqlite3.InternalError

  Exception raised when SQLite encounters an internal error. If this is raised, it may indicate that there is a problem with the runtime SQLite library. `InternalError` is a subclass of `DatabaseError`.

exception sqlite3.ProgrammingError

  Exception raised for `sqlite3` API programming errors, for example supplying the wrong number of bindings to a query, or trying to operate on a closed `Connection`. `ProgrammingError` is a subclass of `DatabaseError`.

exception sqlite3.NotSupportedError

  Exception raised in case a method or database API is not supported by the underlying SQLite library. For example, setting deterministic to `True` in `create_function()`, if the underlying SQLite library does not support deterministic functions. `NotSupportedError` is a subclass of `DatabaseError`.

### SQLite and Python types

SQLite natively supports the following types: `NULL`, `INTEGER`, `REAL`, `TEXT`, `BLOB`.

The following Python types can thus be sent to SQLite without any problem:

Python type | SQLite type
--- | ---
`None` | `NULL`
`int` | `INTEGER`
`float` | `REAL`
`str` | `TEXT`
`bytes` | `BLOB`

This is how SQLite types are converted to Python types by default:

SQLite type | Python type
--- | ---
`NULL` | `None`
`INTEGER` | `int`
`REAL` | `float`
`TEXT` | depends on `text_factory`, `str` by default
`BLOB` | `bytes`

The type system of the `sqlite3` module is extensible in two ways: you can store additional Python types in an SQLite database via object adapters, and you can let the `sqlite3` module convert SQLite types to Python types via converters.

## How-to guides

### Using placeholders to bind values in SQL queries

SQL operations usually need to use values from Python variables. However, beware of using Python’s string operations to assemble queries, as they are vulnerable to SQL injection attacks (see the xkcd webcomic for a humorous example of what can go wrong):

    # Never do this -- insecure!
    symbol = 'RHAT'
    cur.execute("SELECT * FROM stocks WHERE symbol = '%s'" % symbol)

Instead, use the DB-API’s parameter substitution. To insert a variable into a query string, use a placeholder in the string, and substitute the actual values into the query by providing them as a `tuple` of values to the second argument of the cursor’s `execute()` method. An SQL statement may use one of two kinds of placeholders: question marks (qmark style) or named placeholders (named style). For the qmark style, `parameters` must be a sequence. For the named style, it can be either a sequence or `dict` instance. The length of the sequence must match the number of placeholders, or a `ProgrammingError` is raised. If a `dict` is given, it must contain keys for all named parameters. Any extra items are ignored. Here’s an example of both styles:

    import sqlite3

    con = sqlite3.connect(":memory:")
    cur = con.cursor()
    cur.execute("create table lang (name, first_appeared)")

    # This is the qmark style:
    cur.execute("insert into lang values (?, ?)", ("C", 1972))

    # The qmark style used with executemany():
    lang_list = [
        ("Fortran", 1957),
        ("Python", 1991),
        ("Go", 2009),
    ]
    cur.executemany("insert into lang values (?, ?)", lang_list)

    # And this is the named style:
    cur.execute("select * from lang where first_appeared=:year", {"year": 1972})
    print(cur.fetchall())

    con.close()

### Using adapters to store custom Python types in SQLite databases

SQLite supports only a limited set of data types natively. To store custom Python types in SQLite databases, adapt them to one of the Python types SQLite natively understands.

There are two ways to adapt Python objects to SQLite types: letting your object adapt itself, or using an adapter callable. The latter will take precedence above the former. For a library that exports a custom type, it may make sense to enable that type to adapt itself. As an application developer, it may make more sense to take direct control by registering custom adapter functions.

#### Letting your object adapt itself

Suppose we have a `Point` class that represents a pair of coordinates, `x` and `y`, in a Cartesian coordinate system. The coordinate pair will be stored as a text string in the database, using a semicolon to separate the coordinates. This can be implemented by adding a `__conform__(self, protocol)` method which returns the adapted value. The object passed to protocol will be of type `PrepareProtocol`.

    import sqlite3

    class Point:
        def __init__(self, x, y):
            self.x, self.y = x, y

        def __conform__(self, protocol):
            if protocol is sqlite3.PrepareProtocol:
                return "%f;%f" % (self.x, self.y)

    con = sqlite3.connect(":memory:")
    cur = con.cursor()

    p = Point(4.0, -3.2)
    cur.execute("select ?", (p,))
    print(cur.fetchone()[0])

    con.close()

#### Registering an adapter callable

The other possibility is to create a function that converts the Python object to an SQLite-compatible type. This function can then be registered using `register_adapter()`.

    import sqlite3

    class Point:
        def __init__(self, x, y):
            self.x, self.y = x, y

    def adapt_point(point):
        return "%f;%f" % (point.x, point.y)

    sqlite3.register_adapter(Point, adapt_point)

    con = sqlite3.connect(":memory:")
    cur = con.cursor()

    p = Point(4.0, -3.2)
    cur.execute("select ?", (p,))
    print(cur.fetchone()[0])

    con.close()

### Converting SQLite values to custom Python types

Writing an adapter lets you convert from custom Python types to SQLite values. To be able to convert from SQLite values to custom Python types, we use converters.

Let’s go back to the `Point` class. We stored the x and y coordinates separated via semicolons as strings in SQLite.

First, we’ll define a converter function that accepts the string as a parameter and constructs a `Point` object from it.

Note

Converter functions are always passed a `bytes` object, no matter the underlying SQLite data type.

    def convert_point(s):
        x, y = map(float, s.split(b";"))
        return Point(x, y)

We now need to tell `sqlite3` when it should convert a given SQLite value. This is done when connecting to a database, using the detect_types parameter of `connect()`. There are three options:

- Implicit: set detect_types to `PARSE_DECLTYPES`

- Explicit: set detect_types to `PARSE_COLNAMES`

- Both: set detect_types to `sqlite3.PARSE_DECLTYPES | sqlite3.PARSE_COLNAMES`. Column names take precedence over declared types.

The following example illustrates the implicit and explicit approaches:

    import sqlite3

    class Point:
        def __init__(self, x, y):
            self.x, self.y = x, y

        def __repr__(self):
            return f"Point({self.x}, {self.y})"

    def adapt_point(point):
        return f"{point.x};{point.y}".encode("utf-8")

    def convert_point(s):
        x, y = list(map(float, s.split(b";")))
        return Point(x, y)

    # Register the adapter and converter
    sqlite3.register_adapter(Point, adapt_point)
    sqlite3.register_converter("point", convert_point)

    # 1) Parse using declared types
    p = Point(4.0, -3.2)
    con = sqlite3.connect(":memory:", detect_types=sqlite3.PARSE_DECLTYPES)
    cur = con.execute("create table test(p point)")

    cur.execute("insert into test(p) values (?)", (p,))
    cur.execute("select p from test")
    print("with declared types:", cur.fetchone()[0])
    cur.close()
    con.close()

    # 2) Parse using column names
    con = sqlite3.connect(":memory:", detect_types=sqlite3.PARSE_COLNAMES)
    cur = con.execute("create table test(p)")

    cur.execute("insert into test(p) values (?)", (p,))
    cur.execute('select p as "p [point]" from test')
    print("with column names:", cur.fetchone()[0])
    cur.close()
    con.close()

### Default adapters and converters

There are default adapters for the date and datetime types in the datetime module. They will be sent as ISO dates/ISO timestamps to SQLite.

The default converters are registered under the name “date” for `datetime.date` and under the name “timestamp” for `datetime.datetime`.

This way, you can use date/timestamps from Python without any additional fiddling in most cases. The format of the adapters is also compatible with the experimental SQLite date/time functions.

The following example demonstrates this.

    import sqlite3
    import datetime

    con = sqlite3.connect(":memory:", detect_types=sqlite3.PARSE_DECLTYPES|sqlite3.PARSE_COLNAMES)
    cur = con.cursor()
    cur.execute("create table test(d date, ts timestamp)")

    today = datetime.date.today()
    now = datetime.datetime.now()

    cur.execute("insert into test(d, ts) values (?, ?)", (today, now))
    cur.execute("select d, ts from test")
    row = cur.fetchone()
    print(today, "=>", row[0], type(row[0]))
    print(now, "=>", row[1], type(row[1]))

    cur.execute('select current_date as "d [date]", current_timestamp as "ts [timestamp]"')
    row = cur.fetchone()
    print("current_date", row[0], type(row[0]))
    print("current_timestamp", row[1], type(row[1]))

    con.close()

If a timestamp stored in SQLite has a fractional part longer than 6 numbers, its value will be truncated to microsecond precision by the timestamp converter.

Note

The default “timestamp” converter ignores UTC offsets in the database and always returns a naive `datetime.datetime` object. To preserve UTC offsets in timestamps, either leave converters disabled, or register an offset-aware converter with `register_converter()`.

### Adapter and converter recipes

This section shows recipes for common adapters and converters.

    import datetime
    import sqlite3

    def adapt_date_iso(val):
        """Adapt datetime.date to ISO 8601 date."""
        return val.isoformat()

    def adapt_datetime_iso(val):
        """Adapt datetime.datetime to timezone-naive ISO 8601 date."""
        return val.isoformat()

    def adapt_datetime_epoch(val)
        """Adapt datetime.datetime to Unix timestamp."""
        return int(val.timestamp())

    sqlite3.register_adapter(datetime.date, adapt_date_iso)
    sqlite3.register_adapter(datetime.datetime, adapt_datetime_iso)
    sqlite3.register_adapter(datetime.datetime, adapt_datetime_epoch)

    def convert_date(val):
        """Convert ISO 8601 date to datetime.date object."""
        return datetime.date.fromisoformat(val)

    def convert_datetime(val):
        """Convert ISO 8601 datetime to datetime.datetime object."""
        return datetime.datetime.fromisoformat(val)

    def convert_timestamp(val):
        """Convert Unix epoch timestamp to datetime.datetime object."""
        return datetime.datetime.fromtimestamp(val)

    sqlite3.register_converter("date", convert_date)
    sqlite3.register_converter("datetime", convert_datetime)
    sqlite3.register_converter("timestamp", convert_timestamp)

### Using connection shortcut methods

Using the `execute()`, `executemany()`, and `executescript()` methods of the `Connection` class, your code can be written more concisely because you don’t have to create the (often superfluous) `Cursor` objects explicitly. Instead, the `Cursor` objects are created implicitly and these shortcut methods return the cursor objects. This way, you can execute a `SELECT` statement and iterate over it directly using only a single call on the `Connection` object.

    import sqlite3

    langs = [
        ("C++", 1985),
        ("Objective-C", 1984),
    ]

    con = sqlite3.connect(":memory:")

    # Create the table
    con.execute("create table lang(name, first_appeared)")

    # Fill the table
    con.executemany("insert into lang(name, first_appeared) values (?, ?)", langs)

    # Print the table contents
    for row in con.execute("select name, first_appeared from lang"):
        print(row)

    print("I just deleted", con.execute("delete from lang").rowcount, "rows")

    # close is not a shortcut method and it's not called automatically,
    # so the connection object should be closed manually
    con.close()

### Accessing columns by name instead of by index

One useful feature of the `sqlite3` module is the built-in `sqlite3.Row` class designed to be used as a row factory.

Rows wrapped with this class can be accessed both by index (like tuples) and case-insensitively by name:

    import sqlite3

    con = sqlite3.connect(":memory:")
    con.row_factory = sqlite3.Row

    cur = con.cursor()
    cur.execute("select 'John' as name, 42 as age")
    for row in cur:
        assert row[0] == row["name"]
        assert row["name"] == row["nAmE"]
        assert row[1] == row["age"]
        assert row[1] == row["AgE"]

    con.close()

### Using the connection as a context manager

A `Connection` object can be used as a context manager that automatically commits or rolls back open transactions when leaving the body of the context manager. If the body of the `with` statement finishes without exceptions, the transaction is committed. If this commit fails, or if the body of the `with` statement raises an uncaught exception, the transaction is rolled back.

If there is no open transaction upon leaving the body of the `with` statement, the context manager is a no-op.

Note

The context manager neither implicitly opens a new transaction nor closes the connection.

    import sqlite3

    con = sqlite3.connect(":memory:")
    con.execute("create table lang (id integer primary key, name varchar unique)")

    # Successful, con.commit() is called automatically afterwards
    with con:
        con.execute("insert into lang(name) values (?)", ("Python",))

    # con.rollback() is called after the with block finishes with an exception, the
    # exception is still raised and must be caught
    try:
        with con:
            con.execute("insert into lang(name) values (?)", ("Python",))
    except sqlite3.IntegrityError:
        print("couldn't add Python twice")

    # Connection object used as context manager only commits or rollbacks transactions,
    # so the connection object should be closed manually
    con.close()

### Working with SQLite URIs

Some useful URI tricks include:

- Open a database in read-only mode:

      con = sqlite3.connect("file:template.db?mode=ro", uri=True)

- Do not implicitly create a new database file if it does not already exist; will raise `OperationalError` if unable to create a new file:

      con = sqlite3.connect("file:nosuchdb.db?mode=rw", uri=True)

- Create a shared named in-memory database:

      con1 = sqlite3.connect("file:mem1?mode=memory&cache=shared", uri=True)
      con2 = sqlite3.connect("file:mem1?mode=memory&cache=shared", uri=True)
      con1.execute("create table t(t)")
      con1.execute("insert into t values(28)")
      con1.commit()
      rows = con2.execute("select * from t").fetchall()

More information about this feature, including a list of parameters, can be found in the SQLite URI documentation.

## Explanation

### Transaction control

The `sqlite3` module does not adhere to the transaction handling recommended by PEP 249.

If the connection attribute `isolation_level` is not `None`, new transactions are implicitly opened before `execute()` and `executemany()` executes `INSERT`, `UPDATE`, `DELETE`, or `REPLACE` statements. Use the `commit()` and `rollback()` methods to respectively commit and roll back pending transactions. You can choose the underlying SQLite transaction behaviour — that is, whether and what type of `BEGIN` statements `sqlite3` implicitly executes – via the `isolation_level` attribute.

If `isolation_level` is set to `None`, no transactions are implicitly opened at all. This leaves the underlying SQLite library in autocommit mode, but also allows the user to perform their own transaction handling using explicit SQL statements. The underlying SQLite library autocommit mode can be queried using the `in_transaction` attribute.

The `executescript()` method implicitly commits any pending transaction before execution of the given SQL script, regardless of the value of `isolation_level`.

Changed in version 3.6: `sqlite3` used to implicitly commit an open transaction before DDL statements. This is no longer the case.