sql-server - 如何删除**IN**查询Sql中的冗余条件

Question

我有这样的疑问。但我需要优化这个查询，这样如何才能使用相同的分割函数省略冗余条件。

DECLARE @Filter nvarchar(20)
SELECT @Filter ='5,22,3'

SELECT * FROM    Employee e
             WHERE e.code IN 
             (
             CASE WHEN((SELECT count(*) FROM dbo.FNSPLITSTRING(SUBSTRING(@Filter,1,LEN(@Filter)-1), ',') d 
                                  WHERE d.splitdata IN (5, 16, 20, 23, 33, 49, 62, 90, 91, 92, 93, 94))>0) THEN 5 ELSE 0 END 
             ,CASE WHEN((SELECT count(*) FROM dbo.FNSPLITSTRING(SUBSTRING(@Filter,1,LEN(@Filter)-1), ',') d 
                                  WHERE d.splitdata IN (22, 18))>0) THEN 46 ELSE 0 END
             ,CASE WHEN((SELECT count(*) FROM dbo.FNSPLITSTRING(SUBSTRING(@Filter,1,LEN(@Filter)-1), ',') d 
                                  WHERE d.splitdata IN (3, 28))>0) THEN 3 ELSE 0 END
             )

Answer 1

正如@Damien_The_Unknowner所说，避免将字符串拆分为值表。您不需要多次分割同一个字符串。相反，您可以使用临时表变量。

DECLARE @SplitStrings TABLE
(
    splitdata int
)

INSERT @SplitStrings
SELECT splitdata FROM dbo.FNSPLITSTRING(SUBSTRING(@Filter,1,LEN(@Filter)-1), ',') d

DECLARE @EmployeeCodes TABLE
(
    splitdata INT,
    code int
)

INSERT @EmployeeCodes (splitdata, code)
VALUES (5, 5), (16, 5), (20, 5), (23, 5), (33, 5), (49, 5), (62, 5), (90, 5), (91, 5), (92, 5), (93, 5), (94, 5), 
       (22, 46), (18, 46),
       (3, 3), (28, 3)


SELECT e.* 
FROM Employee e
JOIN @EmployeeCodes ec
ON e.code = ec.code
JOIN @SplitStrings ss
ON ec.splitdata = ss.splitdata

我希望这是您正在寻找的方向。

注意:假设您不需要 0 作为员工代码。