Question

如何将来自不同表的多个选择计数（*）组合成一个回报？

我有与此post

类似的情境

但我想要一次回归。

我尝试了所有的联盟，但它吐了3个不同的计数行。你如何将它们合二为一？

select count(*) from foo1 where ID = '00123244552000258'
union all 
select count(*) from foo2 where ID = '00123244552000258'
union all
select count(*) from foo3 where ID = '00123244552000258'

编辑：我正在使用MS SQL 2005

Answer 1

SELECT 
(select count(*) from foo1 where ID = '00123244552000258')
+
(select count(*) from foo2 where ID = '00123244552000258')
+
(select count(*) from foo3 where ID = '00123244552000258')

这是一种简单的方法。

Answer 2

我很惊讶没有人建议这种变化：

SELECT SUM(c)
FROM (
  SELECT COUNT(*) AS c FROM foo1 WHERE ID = '00123244552000258'
  UNION ALL
  SELECT COUNT(*) FROM foo2 WHERE ID = '00123244552000258'
  UNION ALL
  SELECT COUNT(*) FROM foo3 WHERE ID = '00123244552000258'
);

Answer 3

select 
  (select count(*) from foo) as foo
, (select count(*) from bar) as bar
, ...

Answer 4

基本上，您将计数作为标准选择中的子查询。

以下是一个例子，它返回1行，两列

SELECT
 (SELECT COUNT(*) FROM MyTable WHERE MyCol = 'MyValue') AS MyTableCount,
 (SELECT COUNT(*) FROM YourTable WHERE MyCol = 'MyValue') AS YourTableCount,

Answer 5

你可以像以前那样合并你的计数，但是你可以通过多种方式对它们进行总结，其中一种如下所示：

SELECT SUM(A) 
FROM
(
    SELECT 1 AS A
    UNION ALL 
    SELECT 1 AS A
    UNION ALL
    SELECT 1 AS A
    UNION ALL
    SELECT 1 AS A
) AS B

Answer 6

您可以为所有字段命名并在这些字段上添加外部选择：

SELECT A, B, C FROM ( your initial query here ) TableAlias

这应该可以解决问题。

Answer 7

select sum(counts) from (
select count(1) as counts from foo 
union all
select count(1) as counts from bar)

Answer 8

对于oracle：

select( 
select count(*) from foo1 where ID = '00123244552000258'
+
select count(*) from foo2 where ID = '00123244552000258'
+
select count(*) from foo3 where ID = '00123244552000258'
) total from dual;

SQL：组合从多个表中选择计数（*）

8 个答案: