这在 SQL Server 中不起作用 - 没有变量类型可以包含 lambda 表达式之类的东西,比如Between (@Number2*10) AND (@Number2*10+9)
.
一种方法是将其存储在字符串中(例如,nvarchar(max))并使用 exec() 或 sp_executesql() 执行。
另一种(通常更优化)的方法是形成主表达式以包括子表达式以及排除标准。
这是一个例子:
DECLARE @Number1 int = 1 -- input variable 1
DECLARE @Number2 int = 1 -- input variable 2
DECLARE @excl1 bit = 0 -- exclusion criteria 1 (ec1)
DECLARE @excl2 bit = 0 -- exclusion criteria 2 (ec2)
-- fill excl. crit.
SET @excl1 = CASE WHEN @Number1 = 1 AND @Number2 = 0 THEN 1 ELSE 0 END
SET @excl2 = CASE WHEN @Number1 = 1 AND @Number2 > 0 THEN 1 ELSE 0 END
-- just output to see what's happening
PRINT @Number1
PRINT @Number2
PRINT @excl1
PRINT @excl2
SELECT *
FROM Table
WHERE
-- if ec1 is active, we apply sub-expression 1
(@excl1 = 0 OR
(@excl1 = 1 AND ID IS NULL))
AND
-- if ec2 is active, we apply sub-expression 2
(@excl2 = 0 OR
(@excl2 = 1 AND ID BETWEEN @Number2 * 10 AND @Number2 * 10 + 9))