sql - IN 语句中的 case 语句

Question

我有一个变量年龄用于我的查询，如下所示：

Declare @age as int 11

Select * from people p where p.age = @age

但是当我在@age 上设置 0 时，我想向所有 10 到 13 岁的人展示，所以我正在尝试做这样的事情：

Select * 
from people p 
where p.age in( case 
                     when @age = 0 
                          then 10, 11, 12, 13
                          else @age
                     end
              )

谁能给我一盏灯？

Answer 1

你不需要CASE声明，你可以WHERE稍微改变你的条款。这应该返回相同的结果：

Select * 
from people p 
where 
( 
    @age = 0 
    AND p.age IN (10, 11, 12, 13)
)
OR
(
    @age != 0 
    AND p.age = @age
)

Answer 2

您不需要 case 语句：

SELECT col1, col2, ..., coln
FROM people AS p 
WHERE (@age = 0 AND p.age BETWEEN 10 AND 13)
OR (@age <> 0 AND p.age = @age)

Answer 3

这似乎最简单

如果业务规则发生变化，也很容易修改。

declare @min int
declare @max int
declare @age int

set @age = 0

if (@age = 0)
begin
   SET @min = 10
   SET @max = 13
end
else
begin
   SET @min = @age
   SET @max = @age
end 

Select * 
from people p 
where age >= @min and age <= @max

Answer 4

select *
from people
where (age between 10 and 13 and @age=0) 
or (age = @age)

Answer 5

您需要将 SELECT 添加到您的 IN() 部分

Select * 
from people p 
where p.age in (SELECT case 
                     when @age = 0 
                          then 10, 11, 12, 13
                          else @age
                     end
              )