[master_user_id] = 1
 [user_id] => Array
        (
            [0] => 11
            [1] => 10
        [2] => 9
        [3] => 8
        [4] => 7
        )
/* how can i generate the string starting form values */
/* i.e. (1,11), (1,10), (1,9), (1,8), (1,7) */
INSERT INTO bm_user_relation (master_user_id , user_id ) VALUES (1,11), (1,10), (1,9), (1,8), (1,7)