Question

我有一个名为'loan'的表，其约束为Loan_Date < Return_Date。我无法在返回日期中插入空值。

构造：CONSTRAINT LOAN_DATE_CK CHECK (Loan_Date < Return_Date)

我的SQL声明：

INSERT INTO Loan (Borrower_Id, Copy_Id, Loan_Date ,Return_Date) VALUES
('00001','00001','2014-04-01','2014-04-10'),
('00001','00007','2014-04-10',' ');

错误：

****Msg 547, Level 16, State 0, Line 1
The INSERT statement conflicted with the CHECK constraint "LOAN_DATE_CK". The conflict occurred in database "lib_database", table "dbo.Loan".
The statement has been terminated.****

我可以输入两个值的记录。任何人都可以帮我纠正这个错误吗？

Answer 1

删除约束或在约束中添加其他条件并将其添加为

CONSTRAINT LOAN_DATE_CK CHECK (Loan_Date < Return_Date OR Return_Date is null)

并按此插入

INSERT INTO Loan (Borrower_Id, Copy_Id, Loan_Date ,Return_Date) VALUES
('00001','00001','2014-04-01','2014-04-10'),
('00001','00007','2014-04-10', null); --make null value instead of ' ' or ''

Answer 2

您可以将约束更改为以下内容：[未经过测试]

 (Loan_Date < ISNULL(Return_Date, '9999-12-01'))

在这种情况下，如果您的返回日期为空，则会忽略它。

Answer 3

我假设Loan_Date，Return_Date字段的类型为Date / DateTime - 您无法针对空值成功评估Date数据类型（2014-01-01＆gt;或＆lt; null）此值将始终返回false

我建议添加一个ISNULL检查条件以返回一个可以检查的静态日期

CONSTRAINT LOAN_DATE_CK CHECK (Loan_Date < ISNULL(Return_Date, CAST('CustomDate' as DATE)))

SQL查询 - 无法插入带有日期检查约束的值 -

3 个答案: