function db_set_active in Drupal 6

Same name and namespace in other branches

1. 8 core/includes/database.inc \db_set_active()
2. 4 includes/database.inc \db_set_active()
3. 5 includes/database.inc \db_set_active()
4. 7 includes/database/database.inc \db_set_active()

Activate a database for future queries.

If it is necessary to use external databases in a project, this function can be used to change where database queries are sent. If the database has not yet been used, it is initialized using the URL specified for that name in Drupal's configuration file. If this name is not defined, a duplicate of the default connection is made instead.

Be sure to change the connection back to the default when done with custom code.

Parameters

$name: The key in the $db_url global variable from settings.php. If omitted, the default connection will be made active.

Return value

The name of the previously active database, or FALSE if none was found.

Related topics

3 calls to db_set_active()

dblog_watchdog in modules/dblog/dblog.module

Implementation of hook_watchdog().

install_main in ./install.php

The Drupal installation happens in a series of steps. We begin by verifying that the current environment meets our minimum requirements. We then go on to verify that settings.php is properly configured. From there we connect to the configured database…

_drupal_bootstrap in includes/bootstrap.inc

File

includes/database.inc, line 124

Wrapper for database interface code.

Code

function db_set_active($name = 'default') {
  global $db_url, $db_type, $active_db;
  static $db_conns, $active_name = FALSE;
  if (empty($db_url)) {
    include_once 'includes/install.inc';
    install_goto('install.php');
  }
  if (!isset($db_conns[$name])) {

    // Initiate a new connection, using the named DB URL specified.
    if (is_array($db_url)) {
      $connect_url = array_key_exists($name, $db_url) ? $db_url[$name] : $db_url['default'];
    }
    else {
      $connect_url = $db_url;
    }
    $db_type = substr($connect_url, 0, strpos($connect_url, '://'));
    $handler = "./includes/database.{$db_type}.inc";
    if (is_file($handler)) {
      include_once $handler;
    }
    else {
      _db_error_page("The database type '" . $db_type . "' is unsupported. Please use either 'mysql' or 'mysqli' for MySQL, or 'pgsql' for PostgreSQL databases.");
    }
    $db_conns[$name] = db_connect($connect_url);
  }
  $previous_name = $active_name;

  // Set the active connection.
  $active_name = $name;
  $active_db = $db_conns[$name];
  return $previous_name;
}