一段存储过程语句,不理解的是return 1,return 2,return 3在语句中有什么作用啊
if(select 是否借出 from Books where 图书编号=@BookID)=1
begin
print'图书已借出,不能借'
return 1
endif(@BorrowNum>=@BorrowDureNum)
begin
print'借书数量已满,不能再借'
return 2
endif exists (select * from Borrow where 读者编号=@ReaderID and
datediff(day,应还日期,getdate())>0)
begin
print'有过期未还图书,不能借'
return 3
end
if(select 是否借出 from Books where 图书编号=@BookID)=1
begin
print'图书已借出,不能借'
return 1
endif(@BorrowNum>=@BorrowDureNum)
begin
print'借书数量已满,不能再借'
return 2
endif exists (select * from Borrow where 读者编号=@ReaderID and
datediff(day,应还日期,getdate())>0)
begin
print'有过期未还图书,不能借'
return 3
end
GO
CREATE PROCEDURE checkstate @param varchar(11)
AS
IF (SELECT StateProvince FROM Person.vAdditionalContactInfo WHERE ContactID = @param) = 'WA'
RETURN 1
ELSE
RETURN 2;
GO
DECLARE @return_status int;
EXEC @return_status = checkstate '2';
SELECT 'Return Status' = @return_status;
GO