Selects the default database for database queries

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- PHP Manual
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- Selects the default database for database queries

# mysqli::select_db

# mysqli_select_db

(PHP 5, PHP 7, PHP 8)

mysqli::select_db -- mysqli_select_db — Selects the default database for database queries

### Description

Object-oriented style

public mysqli::select_db(string `$database`): bool

Procedural style

mysqli_select_db(mysqli `$mysql`, string `$database`): bool

Selects the default database to be used when performing queries against the database connection.

> Note:

> This function should only be used to change the default database for the connection. You can select the default database with 4th parameter in mysqli_connect().

### Parameters

`mysql`

  Procedural style only: A mysqli object returned by mysqli_connect() or mysqli_init()

`database`

  The database name.

### Return Values

Returns `true` on success or `false` on failure.

### Errors/Exceptions

If mysqli error reporting is enabled (`MYSQLI_REPORT_ERROR`) and the requested operation fails, a warning is generated. If, in addition, the mode is set to `MYSQLI_REPORT_STRICT`, a mysqli_sql_exception is thrown instead.

### Examples

Example #1 mysqli::select_db() example

Object-oriented style

    <?phpmysqli_report(MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT);$mysqli = new mysqli("localhost", "my_user", "my_password", "test");/* get the name of the current default database */$result = $mysqli->query("SELECT DATABASE()");$row = $result->fetch_row();printf("Default database is %s.\n", $row[0]);/* change default database to "world" */$mysqli->select_db("world");/* get the name of the current default database */$result = $mysqli->query("SELECT DATABASE()");$row = $result->fetch_row();printf("Default database is %s.\n", $row[0]);

Procedural style

    <?phpmysqli_report(MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT);$link = mysqli_connect("localhost", "my_user", "my_password", "test");/* get the name of the current default database */$result = mysqli_query($link, "SELECT DATABASE()");$row = mysqli_fetch_row($result);printf("Default database is %s.\n", $row[0]);/* change default database to "world" */mysqli_select_db($link, "world");/* get the name of the current default database */$result = mysqli_query($link, "SELECT DATABASE()");$row = mysqli_fetch_row($result);printf("Default database is %s.\n", $row[0]);

The above examples will output:

    Default database is test.
    Default database is world.

### See Also

- mysqli_connect() - Alias of mysqli::__construct
- mysqli_real_connect() - Opens a connection to a mysql server