wpdb::db_version() – Method | Developer.WordPress.org

Retrieves the database server version.

Return

string|null Version number on success, null on failure.

public function db_version() {
	return preg_replace( '/[^0-9.].*/', '', $this->db_server_info() );
}

Uses	Description
wpdb::db_server_info()`wp-includes/class-wpdb.php`	Returns the version of the MySQL server.

Used by	Description
WP_Automatic_Updater::should_update()`wp-admin/includes/class-wp-automatic-updater.php`	Tests to see if we can and should update a specific item.
dbDelta()`wp-admin/includes/upgrade.php`	Modifies the database based on specified SQL statements.
update_core()`wp-admin/includes/update-core.php`	Upgrades the core of WordPress.
list_core_update()`wp-admin/update-core.php`	Lists available core updates.
wp_version_check()`wp-includes/update.php`	Checks WordPress version against the newest version.
wpdb::check_database_version()`wp-includes/class-wpdb.php`	Determines whether MySQL database is at least the required minimum version.
wpdb::has_cap()`wp-includes/class-wpdb.php`	Determines whether the database or WPDB supports a particular feature.

Version	Description
2.7.0	Introduced.