Title: wpdb::set_blog_id
Published: April 25, 2014
Last modified: May 20, 2026

---

# wpdb::set_blog_id( int $blog_id, int $network_id ): int

## In this article

 * [Parameters](https://developer.wordpress.org/reference/classes/wpdb/set_blog_id/?output_format=md#parameters)
 * [Return](https://developer.wordpress.org/reference/classes/wpdb/set_blog_id/?output_format=md#return)
 * [Source](https://developer.wordpress.org/reference/classes/wpdb/set_blog_id/?output_format=md#source)
 * [Related](https://developer.wordpress.org/reference/classes/wpdb/set_blog_id/?output_format=md#related)
 * [Changelog](https://developer.wordpress.org/reference/classes/wpdb/set_blog_id/?output_format=md#changelog)

[ Back to top](https://developer.wordpress.org/reference/classes/wpdb/set_blog_id/?output_format=md#wp--skip-link--target)

Sets blog ID.

## 󠀁[Parameters](https://developer.wordpress.org/reference/classes/wpdb/set_blog_id/?output_format=md#parameters)󠁿

 `$blog_id`intrequired

`$network_id`intoptional

Network ID. Default 0.

## 󠀁[Return](https://developer.wordpress.org/reference/classes/wpdb/set_blog_id/?output_format=md#return)󠁿

 int Previous blog ID.

## 󠀁[Source](https://developer.wordpress.org/reference/classes/wpdb/set_blog_id/?output_format=md#source)󠁿

    ```php
    public function set_blog_id( $blog_id, $network_id = 0 ) {
    	if ( ! empty( $network_id ) ) {
    		$this->siteid = $network_id;
    	}

    	$old_blog_id  = $this->blogid;
    	$this->blogid = $blog_id;

    	$this->prefix = $this->get_blog_prefix();

    	foreach ( $this->tables( 'blog' ) as $table => $prefixed_table ) {
    		$this->$table = $prefixed_table;
    	}

    	foreach ( $this->tables( 'old' ) as $table => $prefixed_table ) {
    		$this->$table = $prefixed_table;
    	}

    	return $old_blog_id;
    }
    ```

[View all references](https://developer.wordpress.org/reference/files/wp-includes/class-wpdb.php/)
[View on Trac](https://core.trac.wordpress.org/browser/tags/7.0/src/wp-includes/class-wpdb.php#L1043)
[View on GitHub](https://github.com/WordPress/wordpress-develop/blob/7.0/src/wp-includes/class-wpdb.php#L1043-L1062)

## 󠀁[Related](https://developer.wordpress.org/reference/classes/wpdb/set_blog_id/?output_format=md#related)󠁿

| Uses | Description | 
| [wpdb::tables()](https://developer.wordpress.org/reference/classes/wpdb/tables/)`wp-includes/class-wpdb.php` |

Returns an array of WordPress tables.

  | 
| [wpdb::get_blog_prefix()](https://developer.wordpress.org/reference/classes/wpdb/get_blog_prefix/)`wp-includes/class-wpdb.php` |

Gets blog prefix.

  |

| Used by | Description | 
| [wp_get_db_schema()](https://developer.wordpress.org/reference/functions/wp_get_db_schema/)`wp-admin/includes/schema.php` |

Retrieve the SQL for creating database tables.

  | 
| [switch_to_blog()](https://developer.wordpress.org/reference/functions/switch_to_blog/)`wp-includes/ms-blogs.php` |

Switches the current blog.

  | 
| [restore_current_blog()](https://developer.wordpress.org/reference/functions/restore_current_blog/)`wp-includes/ms-blogs.php` |

Restores the current blog, after calling [switch_to_blog()](https://developer.wordpress.org/reference/functions/switch_to_blog/) .

  |

## 󠀁[Changelog](https://developer.wordpress.org/reference/classes/wpdb/set_blog_id/?output_format=md#changelog)󠁿

| Version | Description | 
| [3.0.0](https://developer.wordpress.org/reference/since/3.0.0/) | Introduced. |

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