MYSQL是否从其他表执行切线查询？

我不太确定在这里放些什么来把这两个连接在一起？

如果一个类别可以有多个

会议ID

，最好在

中使用
，而不是
=
，这样它就不会产生错误

where meetingID = [[WHERE IT MATCHES]] (select meetingID from meeting where categoryID = '1')

另一种方法是加入他们，例如

SELECT ...
FROM ....
where meetingID IN (select meetingID 
                    from meeting 
                     where categoryID = '1')

使用JOIN可以提高性能

SELECT DISTINCT a.*
FROM   tableName a
       INNER JOIN meeting b
           ON a.meetingID = b.meetingID 
WHERE  b.categoryID  = '1'

或

SELECT ... 
FROM tablea a 
INNER JOIN meeting m ON a.meetingID = m.meetingID AND m.categoryID = '1'

检查此链接
这是什么
[[匹配的地方]]
？也许你可以解释得更多。
SELECT ... 
FROM tablea a 
INNER JOIN (SELECT meetingID 
            FROM meeting 
            WHERE categoryID = '1'
          ) b ON a.meetingID = b.meetingID;