Question

我正在尝试进行查询，但我无法掌握它。我想通过某些meta_keys选择所有记录。当我通过一个元键查询时，它工作正常。但是当我想通过两个meta_key进行查询时，它什么也没有返回。有人可以帮帮我吗？！

有效的查询：

SELECT *
FROM `uszc_users` AS u, `uszc_utilizatori_acord` AS ua, `uszc_usermeta` AS ub
WHERE ua.email = u.user_email
AND ub.user_id = u.id
AND ub.meta_key = 'first_name'
AND acord = 'DA'
LIMIT 0 , 30

并且不返回任何内容的查询：

SELECT *
FROM `uszc_users` AS u, `uszc_utilizatori_acord` AS ua, `uszc_usermeta` AS ub
WHERE ua.email = u.user_email
AND ub.user_id = u.id
AND ub.meta_key = 'first_name'
AND ub.meta_key = 'last_name'
AND acord = 'DA'
LIMIT 0 , 30

我有3个表，表uszc_usermeta包含first_name和last_name，它们都在meta_value列中。

Answer 1

您要求meta_key等于两个＆＃39; first_name＆＃39;和＆＃39; last_name＆＃39;。您可能想要执行AND ub.meta_key IN ('first_name', 'last_name')。

之类的操作

SELECT *
FROM `uszc_users` AS u, `uszc_utilizatori_acord` AS ua, `uszc_usermeta` AS ub
WHERE ua.email = u.user_email
AND ub.user_id = u.id
AND ub.meta_key IN ('first_name', 'last_name')
AND acord = 'DA'
LIMIT 0 , 30

Answer 2

您无法使用

创建任何记录

AND ub.meta_key = 'first_name'
AND ub.meta_key = 'last_name'

这没有任何意义，所以就这么简单：

SELECT *
FROM `uszc_users` AS u, `uszc_utilizatori_acord` AS ua, `uszc_usermeta` AS ub
WHERE ua.email = u.user_email
AND ub.user_id = u.id
AND (ub.meta_key = 'first_name'
OR ub.meta_key = 'last_name')
AND acord = 'DA'
LIMIT 0 , 30

更新由于OP说@bhelmet发布了正确的答案我想澄清OP 好查询应该如何看起来像imho：

SELECT u.*, ub.meta_value first_name, uc.meta_value last_name
FROM `uszc_users` AS u  
INNER JOIN `uszc_utilizatori_acord` AS ua
ON ua.email = u.user_email
  AND ua.acord = 'DA'
INNER JOIN  `uszc_usermeta` AS ub
ON ub.user_id = u.id
  AND ub.meta_key = 'first_name'
INNER JOIN `uszc_usermeta` AS uc
ON uc.user_id = u.id
  AND uc.meta_key = 'last_name'
LIMIT 0 , 30

Answer 3

要检查'usermeta'的两个条件，您应该连接两次表。你需要这样的东西：

SELECT *
FROM `uszc_users` AS u, `uszc_utilizatori_acord` AS ua, `uszc_usermeta` AS ub, `uszc_usermeta` AS uc
WHERE ua.email = u.user_email
AND ub.user_id = u.id
AND ub.meta_key = 'first_name'
AND uc.user_id = u.id
AND uc.meta_key = 'last_name'
AND acord = 'DA'
LIMIT 0 , 30

如何选择某些meta_key的所有元值？

3 个答案: