Question

我正在尝试从users的表中进行子选择。

但我得到一个错误说 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 'AS n1 ) LIMIT 0, 25' at line 7

我不明白我在这里做错了什么

SELECT * FROM ( SELECT 
               n1.userid,
               n1.country,
               n1.gender
               FROM users 
               WHERE n1.country = 'US' 
               AND n1.gender = '1' AS n1 )

Answer 1

我认为这就是你想要的：

SELECT *
FROM (SELECT n1.userid, n1.country,  n1.gender
      FROM users n1
      WHERE n1.country = 'US' AND n1.gender = '1' 
     ) n1;

as不属于WHERE条款。如果要使用它来限定列名，则需要n1作为子查询中的表别名。并且，您应该为外部查询提供表别名。

注意：显然不需要子查询，但我猜你真的想要它来解决你的实际问题。

Answer 2

你确实把别名放在了错误的地方。尝试

SELECT * FROM (SELECT 
               n1.userid,
               n1.country,
               n1.gender
               FROM users AS n1  -- <AS n1> this should be here
               WHERE n1.country = 'US' 
               AND n1.gender = '1')

或

SELECT * FROM (SELECT 
               n1.userid,
               n1.country,
               n1.gender
               FROM users 
               WHERE n1.country = 'US' 
               AND n1.gender = '1') AS n1  -- or here

但是，如果查询不仅仅是一个简化的表单，那么整个查询也可以在没有子查询的情况下编写：

SELECT userid, country, gender
FROM users 
WHERE country = 'US' 
AND gender = '1'

Answer 3

它应该如下所示，因为AS n1指的是内联视图别名。同样，您尝试使用相同的别名来引用子查询中的列，这是另一个错误。

SELECT * FROM ( SELECT 
               userid,
               country,
               gender
               FROM users 
               WHERE country = 'US' 
               AND gender = '1') AS n1

如何在子SELECT内使用WHERE？

3 个答案: