[英]MySQL INNER join depending if php variable equal to a field
I am struggling with an SQL query on the inner join. 我正在努力对内部联接进行SQL查询。 I want to have it so it joins on the field not the same as the $user_id.
我想拥有它,以便它加入与$ user_id不同的字段。 Hope that made sense, this might be easier to understand:
希望这可能更容易理解:
if ($user_id = wallfriends.mem_id_from) {
INNER JOIN wallfriends ON wallusers.mem_id = wallfriends.mem_id_to
} else if ($user_id = wallfriends.mem_id_to) {
INNER JOIN wallfriends ON wallusers.mem_id = wallfriends.mem_id_from
}
My Current query: 我当前的查询:
SELECT * FROM wallusers
INNER JOIN wallfriends ON wallusers.mem_id = wallfriends.mem_id_from
WHERE ((wallfriends.mem_id_from =".$user_id.") OR (wallfriends.mem_id_to =".$user_id.")) AND wallfriends.confirm=1
Thanks in advance 提前致谢
I think what you need is a putting a ternary comparison on the sql string 我认为您需要的是在sql字符串上进行三元比较
$sql = " SELECT * FROM wallusers
INNER JOIN wallfriends ON wallusers.mem_id = ".( $user_id == "wallfriends.mem_id_to"?"wallfriends.mem_id_from":"wallfriends.mem_id_to")."
WHERE wallfriends.confirm=1";
Try this :: 尝试这个 ::
SELECT *
FROM wallusers
INNER JOIN wallfriends ON wallusers.mem_id = wallfriends.mem_id_from
WHERE
(wallfriends.mem_id_from =".$user_id.")
OR
(wallfriends.mem_id_to =".$user_id.")
SELECT * FROM wallusers
INNER JOIN wallfriends ON
wallusers.mem_id =
CASE WHEN
wallfriends.mem_id_from =".$user_id."
THEN wallfriends.mem_id_to
ELSE wallfriends.mem_id_from
END
WHERE wallfriends.confirm=1
声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.