添加几个COUNT个查询的结果

Question

我试图在一个查询中获取几个计数的总和:

SELECT(
    SELECT COUNT( * )
    FROM comments +
    SELECT COUNT( * )
    FROM tags +
    SELECT COUNT( * )
    FROM search
)

我在这里遗漏了一些东西.我得到语法错误.

Answer 1

SELECT ( SELECT COUNT(*) FROM comments ) 
     + ( SELECT COUNT(*) FROM tags ) 
     + ( SELECT COUNT(*) FROM search )

Answer 2

还有一个(不确定是否支持MySQL,但是 - 在SQL Server中有效):

SELECT SUM(Counts) FROM
  (SELECT COUNT(*) AS Counts FROM COMMENTS UNION ALL
   SELECT COUNT(*) FROM Tags UNION ALL
   SELECT COUNT(*) FROM Search) s