TSQL替代方法,用于游标循环遍历更新触发数据 [英] TSQL alternative for cursor to loop over Update-trigger data
问题描述
在此案例
由于性能原因,建议不要使用游标。在更新触发器中循环更新数据的最佳实践是什么?
it was suggested that I should not use cursor because of performance reasons. What are the best practices to loop over the update data in an update trigger ?
UPDATE:
以下是创建该更新触发器的TSQL。
The following is the TSQL for the creation of that update trigger.
CREATE TRIGGER [dbo].[trAfterUpdateInfoDoc]
ON [dbo].[InfoDocs]
AFTER UPDATE
AS
BEGIN
DECLARE @infodoctemplateid INT;
DECLARE @infodocid INT;
DECLARE @requireccount FLOAT(2);
DECLARE @filledcount FLOAT(2);
DECLARE @pcnt FLOAT(2);
DECLARE c CURSOR FOR
SELECT id
FROM InfoDocs ifd
WHERE exists (SELECT 1 FROM Inserted AS i WHERE i.id = ifd.id)
OPEN c
FETCH NEXT FROM c INTO @infodocid
WHILE @@Fetch_Status = 0
BEGIN
SELECT @infodoctemplateid = InfoDocTemplateId
FROM InfoDocs
WHERE id = @infodocid;
SELECT @requireccount = COUNT(*)
FROM InfoDocTemplateFields
WHERE InfoDocTemplateId = @infodoctemplateid
AND IsRequired = 1;
IF (@requireccount = 0)
BEGIN
set @pcnt = 100;
END
ELSE
BEGIN
select @filledcount = count(*) from InfoDocFields
where InfoDocId = @infodocid
and InfoDocTemplateFieldId in (select id from InfoDocTemplateFields where InfoDocTemplateId = @infodoctemplateid and IsRequired = 1)
and (BooleanValue is not null or (StringValue is not null and StringValue <> '') or IntValue is not null or DateValue is not null)
set @pcnt = @filledcount / @requireccount * 100.0;
END
update InfoDocs set PercentageCompleted = @pcnt Where id = @infodocid;
Fetch next From c into @infodocid
End
Close c
Deallocate c
END
推荐答案
我尝试将光标转换为基于集合的代码,但是我无法测试我的解决方案是正确的,昨晚我没睡很多,所以我可能在这里和那里错过了一些事情,它可能比我编写的代码更短,更有效,但是它应该可以给您带来很好的开始的地方:
I've tried translating your cursor into a set based code, however there is no way for me to test if my solution is correct, and I didn't get much sleep last night so I might have missed some things here and there - and it probably can be a shorter and more efficient code than what I've written, but it should give you a good place to start:
CREATE TRIGGER [dbo].[trAfterUpdateInfoDoc]
ON [dbo].[InfoDocs]
AFTER UPDATE
AS
BEGIN
WITH CTE1 AS
(
SELECT ifd.Id,
SUM(CASE WHEN IsRequired = 1 THEN 1 ELSE 0 END) As RequiredCount,
(
select count(*)
from InfoDocFields
where InfoDocFields.InfoDocId = ifd.Id,
and InfoDocTemplateFieldId in (
select id
from InfoDocTemplateFields
where InfoDocTemplateId = idtf.InfoDocTemplateId
and IsRequired = 1
)
and
InfoDocFields.BooleanValue is not null
or (InfoDocFields.StringValue is not null and InfoDocFields.StringValue <> '')
or InfoDocFields.IntValue is not null
or InfoDocFields.DateValue is not null
) As Filledcount
FROM InfoDocs ifd
JOIN InfoDocTemplateFields idtf
ON ifd.InfoDocTemplateId = idtf.InfoDocTemplateId
WHERE exists (SELECT 1 FROM Inserted AS i WHERE i.id = ifd.id)
GROUP BY ifd.Id, idtf.InfoDocTemplateId
), CTE2 AS
(
SELECT ifd.Id,
CASE WHEN RequiredCount = 0 THEN
100
ELSE
Filledcount / RequiredCount * 100.0
END As Completed
FROM CTE1
)
UPDATE docs
SET PercentageCompleted = Completed
FROM InfoDocs docs
JOIN cte2
ON docs.id = cte2.Id
END
这篇关于TSQL替代方法,用于游标循环遍历更新触发数据的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!