Question

我想为自己的虚拟目的创建一个表，但我希望它如下：

2列，“打开”和“付费”。当pay为0 / null时，open必须为1000。open为null / 0则必须为1000。我不确定如何将其烘焙到CREATE TABLE语句中！你能指出我正确的方向吗？

Answer 1

您可以在CREATE TABLE语句中使用CHECK CONSTRAINT来完成此操作。

Answer 2

如果我理解的正确，那么您希望两列的值都可以与0/null不同，或者当其中一列具有0/null时，另一列应该为1000吗？

这可以通过如下检查约束来完成：

create table #test (
  [Open] int null,
  Paid int null,

  constraint CK_Values check ( (isnull([Open], 0) <> 0) and (isnull([Paid], 0) <> 0)
                               or
                               ((isnull([Open], 0) = 0 and Paid is not null and Paid = 1000) or (isnull([Paid], 0) = 0 and [Open] is not null and [Open] = 1000))
                             )  
)

insert into #test values (1, 2)       -- success
insert into #test values (0, 1000)    -- success
insert into #test values (null, 1000) -- success
insert into #test values (1000, 0)    -- success
insert into #test values (1000, null) -- success

insert into #test values (0, 2)       -- fails
insert into #test values (null, 2)    -- fails
insert into #test values (2, 0)       -- fails
insert into #test values (2, null)    -- fails
insert into #test values (null, null) -- fails
insert into #test values (0, 0)       -- fails

Answer 3

您将无法仅使用create table语句来完成此操作。如果要使其工作，还需要触发器（更新后和插入后）。另外，您需要定义如果同时向两列插入或更新0或null会发生什么情况。

如果您的餐桌是：

create table dummy (your_pk int primary key, open numeric(18,2), paid numeric(18,2));

您可以使用这样的触发器：

CREATE TRIGGER dummy_trg_ins 
ON  dummy  
AFTER INSERT 
AS  
BEGIN 
    UPDATE dummy
    SET paid = 1000
    FROM Tb
    INNER JOIN inserted i on i.your_pk = dummy.your_pk
    WHERE i.open is null or i.open = 0
    UPDATE dummy
    SET open = 1000
    FROM Tb
    INNER JOIN inserted i on i.your_pk = dummy.your_pk
    WHERE i.paid is null or i.paid = 0
END  
GO

类似地，您将需要一个更新触发器：

CREATE TRIGGER dummy_trg_upd 
ON  dummy 
AFTER UPDATE 
AS  
BEGIN 
    UPDATE dummy
    SET paid = 1000
    FROM Tb
    INNER JOIN updated i on i.your_pk = dummy.your_pk
    WHERE i.open is null or i.open = 0
    UPDATE dummy
    SET open = 1000
    FROM Tb
    INNER JOIN updated i on i.your_pk = dummy.your_pk
    WHERE i.paid is null or i.paid = 0
END  
GO

创建表时，其他列不可以为null，并且解决方法

3 个答案: