Question

我不是功能专家。继承了以下非常慢的功能

ALTER FUNCTION [dbo].[fn_Diagnosed]
( @clientId As int)
RETURNS NVARCHAR(10)
AS
BEGIN
DECLARE @result  int;
Declare @return nvarchar(10);
set @result = (SELECT COUNT(*)
FROM  dbo.AdditionalInfo 
WHERE  dbo.AdditionalInfo.Type = 'Diagnosed' and  ClientId = @ClientId);
IF @result > 0
   set @return = 'Yes'
ELSE
   set @return = 'No';    
return @return;
END

这是编写函数的正确方法吗？

Answer 1

您的功能看起来不错。不会根据外键约束自动创建索引。因此，您应该像这样显式添加索引

CREATE INDEX ClientAdditionalInfo_ClientID
    ON [dbo].[ClientAdditionalInfo]
    (ClientID)
    INCLUDE ([Type])

SQL函数很慢

1 个答案: