SQL：从多个表中组合选择计数（*）
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SQL: Combine Select count(*) from multiple tables
提问by Hyman
How do you combine multiple select count(*) from different table into one return?
如何将不同表中的多个 select count(*) 合并为一个 return？
I have a similar sitiuation as this post
我和这个帖子有类似的情况
but I want one return.
但我想要一个回报。
I tried Union all but it spit back 3 separate rows of count. How do you combine them into one?
我尝试了 Union all，但它吐出 3 个单独的计数行。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'
edit: I'm on MS SQL 2005
编辑：我在 MS SQL 2005
回答by Chris J
SELECT
(select count(*) from foo1 where ID = '00123244552000258')
+
(select count(*) from foo2 where ID = '00123244552000258')
+
(select count(*) from foo3 where ID = '00123244552000258')
This is an easy way.
这是一个简单的方法。
回答by Remus Rusanu
select
(select count(*) from foo) as foo
, (select count(*) from bar) as bar
, ...
回答by Bill Karwin
I'm surprised no one has suggested this variation:
我很惊讶没有人提出这种变化：
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'
);
回答by Mitchel Sellers
Basically you do the counts as sub-queries within a standard select.
基本上，您将计数作为标准选择中的子查询。
An example would be the following, this returns 1 row, two columns
一个例子如下，这将返回 1 行，两列
SELECT
(SELECT COUNT(*) FROM MyTable WHERE MyCol = 'MyValue') AS MyTableCount,
(SELECT COUNT(*) FROM YourTable WHERE MyCol = 'MyValue') AS YourTableCount,
回答by Jason
You can combine your counts like you were doing before, but then you could sum them all up a number of ways, one of which is shown below:
您可以像以前一样组合您的计数，但随后您可以通过多种方式将它们汇总起来，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
回答by Gren
select sum(counts) from (
select count(1) as counts from foo
union all
select count(1) as counts from bar)
回答by toquart
For oracle:
对于甲骨文：
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;
回答by Kris
you could name all fields and add an outer select on those fields:
您可以命名所有字段并在这些字段上添加外部选择：
SELECT A, B, C FROM ( your initial query here ) TableAlias
That should do the trick.
这应该够了吧。
