无法声明变量 SQL

Question

我一直在尝试声明一个整数变量，但它不起作用。这是我的查询：

DECLARE @count INT
SET     @count = 5633

SELECT count(matchid) 
FROM   `matches`
WHERE   id = @count

我收到此错误：

Error Code: 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 'DECLARE @count INT
SET     @count = 5633

请帮忙 ：）

Answer 1

根据MySQL 手册，DECLARE 只允许在 BEGIN ... END 块内，并且必须位于开始处。您还忘记了每行末尾的分号。这应该适合你：

SET @count = 5633;

SELECT count(*) 
FROM matches
WHERE id = @count;

COUNT(*)在某些情况下更快。

Answer 2

DECLARE @count INT
SET     @count = 5633

SELECT count(matchid) 
FROM    matches  //<===  should be table name
WHERE   id = @count