Question

我经常发现自己在sql server 2005中执行以下操作：

第1步：

create view view1 as 
select count(*) as delivery_count, clientid from deliveries group by clientid;

第2步：

create view view2 as 
select count(*) as action_count, clientid from routeactions group by clientid;

第3步：

select * from view1 inner join view2 on view1.clientid = view2.clientid

是否可以仅在一个语句中获得相同的最终结果，从而避免创建视图？

Answer 1

当然，使用嵌套查询：

select *
from (select count(*) as delivery_count, clientid 
      from deliveries group by clientid) AS view1
inner join (select count(*) as action_count, clientid
            from routeactions group by clientid) AS view2
    on view1.clientid = view2.clientid

或者使用新的CTE语法，您可以：

WITH view1 AS (
    select count(*) as delivery_count, clientid from deliveries group by clientid
), view2 AS (
    select count(*) as action_count, clientid from routeactions group by clientid
)
select * from view1 inner join view2 on view1.clientid = view2.clientid

Answer 2

除非在你没有提及的路线和交付之间存在某种关系，否则我无法想到任何方式。没有它（很可能是从一个到另一个的FK），你不能在不扭曲一个或两个表上的数字的情况下进行连接。

Answer 3

SELECT
    clientid,
    (SELECT COUNT(*) FROM deliveries where clientid = clientIds.clientid) AS 'delivery_count',
    (SELECT COUNT(*) FROM routeactions WHERE clientid = clientIds.clientid)
AS 'action_count'
FROM
(
SELECT clientid FROM deliveries
UNION
SELECT clientid FROM routeactions
) clientIds

我相信这应该有效，如果你有一个客户表

，有更简单的解决方案

请求在SQL Server 2005中使用GROUP BY子句加入其他两个请求的结果

3 个答案: