[ad_1] Hello will be printed out N times. assume N is 3. 1st iteration i = 0 i is less than N print hello i = i + 1; // i = 1 2nd iteration i = 1; i` is less thanN (3)` print hello i = i + 1; // i = 2 3rd … Read more
[ad_1] Add field friendship_key: ALTER TABLE t_friend ADD friendship_key decimal(22,11); CREATE UNIQUE INDEX friendship_key_unique ON t_friend (friendship_key); And php part: $friends = [$userId, $friendId]; $key = min($friends).’.’.max($friends); $q = “SELECT * FROM t_friend WHERE friendship_key = “.$key; insert: $friends = [$userId, $friendId]; $key = min($friends).’.’.max($friends); $q = “INSERT INTO t_friend (friendship_key, userId, friendId) VALUES (“.implode(‘,’, … Read more