更改SUM会将NULL返回零
我有一个存储过程，如下所示：CREATE PROC .
(@SiteName varchar(200))
AS
SELECT
(
SELECT SUM(i.Logged)
FROM tbl_Sites s
INNER JOIN tbl_Incidents i
ON s.Location = i.Location
WHERE s.Sites = @SiteName AND i. = DATEADD(mm, DATEDIFF(mm, 0, GetDate()) -1,0)
GROUP BY s.Sites
)AS LoggedIncidents
'tbl_Sites contains a list of reported on sites.
'tbl_Incidents contains a generated list of total incidents by site/date (monthly)
'If a site doesn't have any incidents that month it wont be listed.
我遇到的问题是，该站点本月没有任何事件，因此当我运行此proc时，我为该站点返回了NULL值，但是我需要返回零/ 0以便在内部使用SSRS中的图表。
我曾尝试使用合并和isull无济于事。
SELECT COALESCE(SUM(c.Logged,0))
SELECT SUM(ISNULL(c.Logged,0))
有没有一种方法可以正确格式化此格式？
干杯，
背风处
解决方案:
放在外面：
SELECT COALESCE(
(
SELECT SUM(i.Logged)
FROM tbl_Sites s
INNER JOIN tbl_Incidents i
ON s.Location = i.Locatio餃﹏
WHERE s.Sites = @SiteName AND i. = DATEADD(mm, DATEDIFF(mm, 0, GetDate()) -1,0)
GROUP BY s.Sites
), 0)AS LoggedIncidents
如果要返回多行，请将INNER JOIN更改为 LEFT JOIN
SELECT COALESCE(SUM(i.Logged),0)
FROM tbl_Sites s
LEFT JOIN tbl_Incidents i
ON s.Location = i.Locatio餃﹏
WHERE s.Sites = @SiteName AND i. = DATEADD(mm, DATEDIFF(mm, 0, GetDate()) -1,0)
GROUP BY s.Sites
顺便说一句，如果没有保证，请勿在聚合函数中放置任何函数或表达式，例如，不要在ISUM中放置ISNULL，COALESCE，在聚合内部使用函数/表达式削弱性能，查询将通过表扫描执行
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