mysql - 这个 UNION ALL mysql 查询有什么问题？

Question

SELECT 'Q' AS TYPE, 
       q.question AS value, 
       q.date
  FROM questions q
 WHERE q.user_id =39
UNION ALL 
SELECT 'A' AS TYPE, 
       q.question AS value, 
       a.date
  FROM answers a,
       questions q
 WHERE a.question_id = q.id
   AND WHERE a.user_id =39
ORDER BY `date` DESC

数据库设计:

• 问题{id,user_id,question,date}
• answers{id,question_id,user_id,answer,date}

错误:

1064 - You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'WHERE a . user_id = 39 ORDER BY date DESC

Answer 1

查询的下半部分有两个 WHERE 子句。您只需要从字面上删除最后一个词 WHERE。错误描述就是您所需要的。