DECLARE @DBName AS NVARCHAR(128)
DECLARE @SQL AS NVARCHAR(200) ;

DECLARE DBCursor CURSOR FAST_FORWARD FOR
    SELECT
           D.name
    FROM
           sys.database_mirroring M
    JOIN
           sys.databases D
    ON
           M.database_id = D.database_id
    WHERE
           mirroring_role_desc = 'PRINCIPAL'


OPEN DBCursor
FETCH NEXT FROM DBCursor
INTO @DBName ;

WHILE @@FETCH_STATUS = 0
BEGIN
    PRINT 'Failing over ' + @DBName + '...' ;

    SELECT @SQL = 'ALTER DATABASE ' + @DBName + ' SET PARTNER FAILOVER' ;

    EXEC(@SQL) ;

    FETCH NEXT FROM DBCursor
    INTO @DBName
END

CLOSE DBCursor ;
DEALLOCATE DBCursor ;