# db2_connect

(PECL ibm_db2 >= 1.0.0)

db2_connect — Returns a connection to a database

### 说明

db2_connect ( string `$database` , string `$username` , string `$password` [, array `$options` ] ) : resource

Creates a new connection to an IBM DB2 Universal Database, IBM Cloudscape, or Apache Derby database.

### 参数

`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;

  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.

  For uncataloged connections, you must pass a `NULL` value or empty string.

`password`

  The password with which you are connecting to the database.

  For uncataloged connections, you must pass a `NULL` value or empty string.

`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.

  `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_connect(). 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_connect() 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: 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.

### 返回值

Returns a connection handle resource if the connection attempt is successful. If the connection attempt fails, db2_connect() returns `FALSE`.

### 范例

Example #1 Creating a cataloged connection

Cataloged connections require you to have previously cataloged the target database through the DB2 Command Line Processor (CLP) or DB2 Configuration Assistant.

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

    $conn = db2_connect($database, $user, $password);

    if ($conn) {
        echo "Connection succeeded.";
        db2_close($conn);
    }
    else {
        echo "Connection failed.";
    }
    ?>

以上例程会输出：

    Connection succeeded.

Example #2 Creating an uncataloged connection

An uncataloged connection enables you to dynamically connect to a database.

    <?php
    $database = 'SAMPLE';
    $user = 'db2inst1';
    $password = 'ibmdb2';
    $hostname = 'localhost';
    $port = 50000;

    $conn_string = "DRIVER={IBM DB2 ODBC DRIVER};DATABASE=$database;" .
      "HOSTNAME=$hostname;PORT=$port;PROTOCOL=TCPIP;UID=$user;PWD=$password;";
    $conn = db2_connect($conn_string, '', '');

    if ($conn) {
        echo "Connection succeeded.";
        db2_close($conn);
    }
    else {
        echo "Connection failed.";
    }
    ?>

以上例程会输出：

    Connection succeeded.

Example #3 Creating a connection with autocommit off by default

Passing an array of options to db2_connect() enables you to modify the default behavior of the connection handle.

    <?php
    $database = 'SAMPLE';
    $user = 'db2inst1';
    $password = 'ibmdb2';
    $options = array('autocommit' => DB2_AUTOCOMMIT_OFF);

    $conn = db2_connect($database, $user, $password, $options);

    if ($conn) {
        echo "Connection succeeded.\n";
        if (db2_autocommit($conn)) {
             echo "Autocommit is on.\n";
        }
        else {
             echo "Autocommit is off.\n";
        }
        db2_close($conn);
    }
    else {
        echo "Connection failed.";
    }
    ?>

以上例程会输出：

    Connection succeeded.
    Autocommit is off.

Example #4 i5/OS best performance

To achieve best performance for your i5/OS ibm_db2 1.5.1 PHP application use the default host, userid, and password for your db2_connect().

    <?php
      $library = "ADC";
      $i5 = db2_connect("", "", "", array("i5_lib"=>"qsys2"));
      $result = db2_exec($i5,
           "select * from systables where table_schema = '$library'");
      while ($row = db2_fetch_both($result)) {
         echo $row['TABLE_NAME']."</br>";
      }
      db2_close($i5);
    ?>

以上例程会输出：

    ANIMALS
    NAMES
    PICTURES

Example #5 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);

    $tc_conn = db2_connect($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";
    }
    ?>

以上例程会输出：

    Explicit trusted connection succeeded.
    User has been switched.

### 参见

- db2_close() - Closes a database connection
- db2_pconnect() - Returns a persistent connection to a database