mysql - 检查子查询返回的内容

Question

我有这样的查询:

INSERT INTO cpus (
    `friendlyname`, `group
) VALUES (
    'something', (SELECT `key` FROM `groups` WHERE `key` = 'something')
);

但是，我想获取子查询的结果。最初我认为它会像

SELECT `key` FROM `groups` WHERE `key` = 'something' AS `result` 

但这没有用。我还应该尝试什么？

Answer 1

您可以使用 MYSQL IF 来检查它是否返回任何内容

试试这个:

INSERT INTO cpus
(
`friendlyname`, 
 `group
) 
VALUES 
(
  'something', 
  IF((SELECT `key` FROM `groups` WHERE `key` = 'something') is null,'Do  something on success','Else' )
);

点击下面的链接了解更多关于 MYSQL 控制流的细节: https://dev.mysql.com/doc/refman/5.0/en/control-flow-functions.html