Question

CREATE TABLE Persons 
(
   ID int NOT NULL,
   ModifiedDate datetime,
   FirstName varchar(50),
   LastName varchar(50),
   EMail varchar(30),
   PhoneNumber varchar(15),
   PRIMARY KEY (ID)
);

GetX (int IDX)

如果参数为null，则返回按ModifiedDate字段降序排列的表的所有行

否则仅返回与ID匹配的行

Answer 1

您想要的是“全部捕获”查询。对于SQL Server，可以通过两种方法完成。 Aaron Bertrand writes about it here.

create procedure GetX (@IDX int = null)
as

select
   ID
   ,ModifiedDate
   ,FirstName
   ,LastName
   ,EMail
   ,PhoneNumber
from Persons
where @IDX is null or ID = @IDX
order by ModifiedDate desc

然后

exec GetX @IDX = 4;
exec GetX @IDX = null;

为名为X的表创建存储过程

1 个答案: