SELECT中的mySQL变量

Question

是否可以进行如下查询:

SELECT
@threadIDvar = `threads`.`id` AS `threadID`,
(SELECT `posts`.`timeDate` FROM `posts` WHERE `posts`.`threadID` = @threadIDvar) AS `postDate`
FROM `threads`
INNER JOIN `posts` ON `posts`.`threadID` = `threads`.`id`
WHERE `threads`.`boardID` = 1

我已经尝试了但是我将@threadID作为NULL返回,因此postDate也为NULL.

如何让变量@threadIDvar填充返回的threadID？

Answer 1

不要忘记:=为用户变量,@threadIDvar :=threads.id