Returns a persistent connection to a database

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- PHP Manual
- IBM DB2 Functions
- Returns a persistent connection to a database

# db2_pconnect

(PECL ibm_db2 >= 1.0.0)

db2_pconnect — Returns a persistent connection to a database

### Description

db2_pconnect(
string `$database`,
?string `$username`,
?string `$password`,
array `$options` = []
): resource|false

Returns a persistent connection to an IBM DB2 Universal Database, IBM Cloudscape, or Apache Derby database.

For more information on persistent connections, refer to Persistent Database Connections.

Calling db2_close() on a persistent connection always returns `true`, but the underlying DB2 client connection remains open and waiting to serve the next matching db2_pconnect() request.

Users running version 1.9.0 or later of ibm_db2 should be aware that the extension will perform a transaction rollback on persistent connections at the end of a request, thus ending the transaction. This prevents the transaction block from carrying over to the next request which uses that connection if script execution ends before the transaction block does.

### Parameters

`database`

  For a cataloged connection to a database, `database` represents the database alias in the DB2 client catalog.

  For an uncataloged connection to a database, `database` represents a complete connection string in the following format:

      DATABASE=database;HOSTNAME=hostname;PORT=port;PROTOCOL=TCPIP;UID=username;PWD=password;

  > Note:

  > When connecting to Db2 on IBM i, the underlying system calls » SQLDriverConnect, which only accepts DSN, UID, and PWD for the » connection string. Like so:

  >     DSN=database;UID=username;PWD=password;

  where the parameters represent the following values:
  `database`

    The name of the database.

  `hostname`

    The hostname or IP address of the database server.

  `port`

    The TCP/IP port on which the database is listening for requests.

  `username`

    The username with which you are connecting to the database.

  `password`

    The password with which you are connecting to the database.

`username`

  The username with which you are connecting to the database.

`password`

  The password with which you are connecting to the database.

`options`

  An associative array of connection options that affect the behavior of the connection, where valid array keys include:

  `autocommit`

    Passing the `DB2_AUTOCOMMIT_ON` value turns autocommit on for this connection handle.

    Passing the `DB2_AUTOCOMMIT_OFF` value turns autocommit off for this connection handle.

  `DB2_ATTR_CASE`

    Passing the `DB2_CASE_NATURAL` value specifies that column names are returned in natural case.

    Passing the `DB2_CASE_LOWER` value specifies that column names are returned in lower case.

    Passing the `DB2_CASE_UPPER` value specifies that column names are returned in upper case.

  `CURSOR`

    Passing the `DB2_FORWARD_ONLY` value specifies a forward-only cursor for a statement resource. This is the default cursor type and is supported on all database servers.

    Passing the `DB2_SCROLLABLE` value specifies a scrollable cursor for a statement resource. This mode enables random access to rows in a result set, but currently is supported only by IBM DB2 Universal Database.

  The following new option is available in ibm_db2 version 1.7.0 and later.

  `trustedcontext`

    Passing the DB2_TRUSTED_CONTEXT_ENABLE value turns trusted context on for this connection handle. This parameter cannot be set using db2_set_option().

    This key works only if the database is cataloged (even if the database is local), or if you specify the full DSN when you create the connection.

    To catalog the database, use following commands:

        db2 catalog tcpip node loopback remote <SERVERNAME> server <SERVICENAME>
        db2 catalog database <LOCALDBNAME> as <REMOTEDBNAME> at node loopback
        db2 "update dbm cfg using svcename <SERVICENAME>"
        db2set DB2COMM=TCPIP

  The following new i5/OS options are available in ibm_db2 version 1.5.1 and later.

  Tip

  Conflicting connection attributes used in conjunction with persistent connections can produce indeterminate results on i5/OS. Site policies should be establish for all applications using each persistent connection user profile. The default DB2_AUTOCOMMIT_ON is suggested when using persistent connections.

  `i5_lib`

    A character value that indicates the default library that will be used for resolving unqualified file references. This is not valid if the connection is using system naming mode.

  `i5_naming`

    `DB2_I5_NAMING_ON` value turns on DB2 UDB CLI iSeries system naming mode. Files are qualified using the slash (/) delimiter. Unqualified files are resolved using the library list for the job.

    `DB2_I5_NAMING_OFF` value turns off DB2 UDB CLI default naming mode, which is SQL naming. Files are qualified using the period (.) delimiter. Unqualified files are resolved using either the default library or the current user ID.

  `i5_commit`

    The `i5_commit` attribute should be set before the db2_pconnect(). If the value is changed after the connection has been established, and the connection is to a remote data source, the change does not take effect until the next successful db2_pconnect() for the connection handle.

    > Note:

    > The php.ini setting `ibm_db2.i5_allow_commit`==0 or `DB2_I5_TXN_NO_COMMIT` is the default, but may be overridden with the `i5_commit` option.

    `DB2_I5_TXN_NO_COMMIT` - Commitment control is not used.

    `DB2_I5_TXN_READ_UNCOMMITTED` - Dirty reads, nonrepeatable reads, and phantoms are possible.

    `DB2_I5_TXN_READ_COMMITTED` - Dirty reads are not possible. Nonrepeatable reads, and phantoms are possible.

    `DB2_I5_TXN_REPEATABLE_READ` - Dirty reads and nonrepeatable reads are not possible. Phantoms are possible.

    `DB2_I5_TXN_SERIALIZABLE` - Transactions are serializable. Dirty reads, non-repeatable reads, and phantoms are not possible

  `i5_query_optimize`

    `DB2_FIRST_IO` All queries are optimized with the goal of returning the first page of output as fast as possible. This goal works well when the output is controlled by a user who is most likely to cancel the query after viewing the first page of output data. Queries coded with an OPTIMIZE FOR nnn ROWS clause honor the goal specified by the clause.

    `DB2_ALL_IO` All queries are optimized with the goal of running the entire query to completion in the shortest amount of elapsed time. This is a good option when the output of a query is being written to a file or report, or the interface is queuing the output data. Queries coded with an OPTIMIZE FOR nnn ROWS clause honor the goal specified by the clause. This is the default.

  `i5_dbcs_alloc`

    `DB2_I5_DBCS_ALLOC_ON` value turns on DB2 6X allocation scheme for DBCS translation column size growth.

    `DB2_I5_DBCS_ALLOC_OFF` value turns off DB2 6X allocation scheme for DBCS translation column size growth.

    > Note:

    > The php.ini setting `ibm_db2.i5_dbcs_alloc`==0 or `DB2_I5_DBCS_ALLOC_OFF` is the default, but may be overridden with the `i5_dbcs_alloc` option.

  `i5_date_fmt`

    `DB2_I5_FMT_ISO` - The International Organization for Standardization (ISO) date format yyyy-mm-dd is used. This is the default.

    `DB2_I5_FMT_USA` - The United States date format mm/dd/yyyy is used.

    `DB2_I5_FMT_EUR` - The European date format dd.mm.yyyy is used.

    `DB2_I5_FMT_JIS` - The Japanese Industrial Standard date format yyyy-mm-dd is used.

    `DB2_I5_FMT_MDY` - The date format mm/dd/yyyy is used.

    `DB2_I5_FMT_DMY` - The date format dd/mm/yyyy is used.

    `DB2_I5_FMT_YMD` - The date format yy/mm/dd is used.

    `DB2_I5_FMT_JUL` - The Julian date format yy/ddd is used.

    `DB2_I5_FMT_JOB` - The job default is used.

  `i5_date_sep`

    `DB2_I5_SEP_SLASH` - A slash ( / ) is used as the date separator. This is the default.

    `DB2_I5_SEP_DASH` - A dash ( - ) is used as the date separator.

    `DB2_I5_SEP_PERIOD` - A period ( . ) is used as the date separator.

    `DB2_I5_SEP_COMMA` - A comma ( , ) is used as the date separator.

    `DB2_I5_SEP_BLANK` - A blank is used as the date separator.

    `DB2_I5_SEP_JOB` - The job default is used

  `i5_time_fmt`

    `DB2_I5_FMT_ISO` - The International Organization for Standardization (ISO) time format hh.mm.ss is used. This is the default.

    `DB2_I5_FMT_USA` - The United States time format hh:mmxx is used, where xx is AM or PM.

    `DB2_I5_FMT_EUR` - The European time format hh.mm.ss is used.

    `DB2_I5_FMT_JIS` - The Japanese Industrial Standard time format hh:mm:ss is used.

    `DB2_I5_FMT_HMS` - The hh:mm:ss format is used.

  `i5_time_sep`

    `DB2_I5_SEP_COLON` - A colon ( : ) is used as the time separator. This is the default.

    `DB2_I5_SEP_PERIOD` - A period ( . ) is used as the time separator.

    `DB2_I5_SEP_COMMA` - A comma ( , ) is used as the time separator.

    `DB2_I5_SEP_BLANK` - A blank is used as the time separator.

    `DB2_I5_SEP_JOB` - The job default is used.

  `i5_decimal_sep`

    `DB2_I5_SEP_PERIOD` - A period ( . ) is used as the decimal separator. This is the default.

    `DB2_I5_SEP_COMMA` - A comma ( , ) is used as the decimal separator.

    `DB2_I5_SEP_JOB` - The job default is used.

  The following new i5/OS option is available in ibm_db2 version 1.8.0 and later.

  `i5_libl`

    A character value that indicates the library list that will be used for resolving unqualified file references. Specify the library list elements separated by blanks 'i5_libl'=>"MYLIB YOURLIB ANYLIB".

    > Note:

    > i5_libl calls qsys2/qcmdexc('cmd',cmdlen), which is only available in i5/OS V5R4 and later.

### Return Values

Returns a connection handle resource if the connection attempt is successful. db2_pconnect() tries to reuse an existing connection resource that exactly matches the `database`, `username`, and `password` parameters. If the connection attempt fails, db2_pconnect() returns `false`.

### Changelog

Version | Description
--- | ---
PECL ibm_db2 1.9.0 | Active transactions within a persistent connection will be rolled back at the end of each request.
PECL ibm_db2 1.8.0 | The `i5_libl` option is available for i5/OS users.
PECL ibm_db2 1.7.0 | The `trustedcontext` option is available.
PECL ibm_db2 1.5.1 | The `i5_lib`, `i5_naming`, `i5_commit`, `i5_query_optimize`, `i5_dbcs_alloc`, `i5_date_fmt`, `i5_date_sep`, `i5_time_fmt`, `i5_time_sep` and `i5_decimal_sep` options are available for i5/OS users.

### Examples

Example #1 A db2_pconnect() example

In the following example, the first call to db2_pconnect() returns a new persistent connection resource. The second call to db2_pconnect() returns a persistent connection resource that simply reuses the first persistent connection resource.

    <?php
    $database = 'SAMPLE';
    $user = 'db2inst1';
    $password = 'ibmdb2';

    $pconn = db2_pconnect($database, $user, $password);

    if ($pconn) {
        echo "Persistent connection succeeded.";
    }
    else {
        echo "Persistent connection failed.";
    }

    $pconn2 = db2_pconnect($database, $user, $password);
    if ($pconn) {
        echo "Second persistent connection succeeded.";
    }
    else {
        echo "Second persistent connection failed.";
    }
    ?>

The above example will output:

    Persistent connection succeeded.
    Second persistent connection succeeded.

Example #2 Using trusted context

The following example shows how to enable trusted context, switch users, and get the current user ID.

    <?php

    $database = "SAMPLE";
    $hostname = "localhost";
    $port = 50000;
    $authID = "db2inst1";
    $auth_pass = "ibmdb2";

    $tc_user = "tcuser";
    $tc_pass = "tcpassword";

    $dsn = "DATABASE=$database;HOSTNAME=$hostname;PORT=$port;
      PROTOCOL=TCPIP;UID=$authID;PWD=$auth_pass;";
    $options = array ("trustedcontext" => DB2_TRUSTED_CONTEXT_ENABLE);

    $tc_conn = db2_pconnect($dsn, "", "", $options);
    if($tc_conn) {
        echo "Explicit trusted connection succeeded.\n";

        if(db2_get_option($tc_conn, "trustedcontext")) {
            $userBefore = db2_get_option($tc_conn, "trusted_user");

            //Do some work as user 1.

            //Switching to trusted user.
            $parameters = array("trusted_user" => $tc_user,
              "trusted_password" => $tcuser_pass);
            $res = db2_set_option ($tc_conn, $parameters, 1);

            $userAfter = db2_get_option($tc_conn, "trusted_user");
            //Do more work as trusted user.

            if($userBefore != $userAfter) {
                echo "User has been switched." . "\n";
            }
        }

        db2_close($tc_conn);
    }
    else {
        echo "Explicit trusted connection failed.\n";
    }
    ?>

The above example will output:

    Explicit trusted connection succeeded.
    User has been switched.

### See Also

- db2_connect() - Returns a connection to a database