当过滤器参数为空时绕过 WHERE 子句

Question

我有一个过程，需要绕过输入为空的 WHERE 子句。

请找出以下条件。

CREATE PROCEDURE [dbo].[spPERSON_SELECT]    
(
@PersonID INT = NULL,
@OrganizationID INT = NULL,
@ManagerID INT = NULL 
)
AS

BEGIN
SELECT PERSON.name, ORGANIZATION.name,PERSON.manager 
FROM PERSON 
    INNER JOIN ORGANIZATION 
        ON PERSON.person_id = ORGANIZATION.person_id    
WHERE PERSON.person_id = @PersonID  
    and ORGANIZATION.organization_id = @OrganizationID  
    and PERSON.manager_id = @ManagerID 

END
GO

当输入为空时我面临一个问题，在这种情况下需要避免 where 条件。

例子：

如果@PersonID 为空，那么我的选择查询需要以下结构：

SELECT PERSON.name, ORGANIZATION.name,PERSON.manager 
FROM PERSON 
    INNER JOIN ORGANIZATION 
        ON PERSON.person_id = ORGANIZATION.person_id    
WHERE ORGANIZATION.organization_id = @OrganizationID
    and PERSON.manager_id = @ManagerID 

我想避免动态查询。

Answer 1

将每个参数括起来并测试是否为空，即

(PERSON.manager_id=@ManagerID or @ManagerID is NUll)

Answer 2

我个人最喜欢的方法是：

WHERE PERSON.manager_id = COALESCE(@ManagerID, PERSON.manager_id)

为每个参数使用coalesce 看起来更好。

即使@ManagerID IS NULL 也会匹配，因为它总是匹配自身PERSON.manager_id，但如果@ManagerID IS NOT NULL 则停止。

值得注意的是，您可以给COALESCE(expression1, expression2, n) 提供任意数量的参数。

Answer 3

SELECT PERSON.name, ORGANIZATION.name, PERSON.manager 
FROM PERSON 
INNER JOIN ORGANIZATION ON PERSON.person_id=ORGANIZATION.person_id
WHERE 
(@PersonID is null or PERSON.person_id=@PersonID) 
and (@OrganizationID is null or ORGANIZATION.organization_id=@OrganizationID)
and (@ManagerID is null or PERSON.manager_id=@ManagerID)