我想在数据库中添加简单的约束。 I follow this添加简单的约束 - 数据库
我的目标:在租户表中,如果LeaseExpirationDate不为NULL,那么它必须晚于LeaseStartDate。
我想:
alter table Tenants
add constraint leasedates_check check (leaseexpirationdate is not null or leaseexpirationdate > leasestartdate);
然后我尝试:
UPDATE
Tenants
SET
leaseexpirationdate = leasestartdate
WHERE
apartmentnumber = 1 and houseid = 100;
该行即使leaseexpirationdate is not null
更新。我错在哪里?我没有比较日期吗?
创建声明:
CREATE TABLE Tenants(
HouseID INT,
ApartmentNumber INT,
LeaseTenantSSN INT NOT NULL,
LeaseStartDate DATE NOT NULL,
LeaseExpirationDate DATE,
Rent DECIMAL(7,2),
LastRentPaidDate DATE,
RentOverdue BOOLEAN,
PRIMARY KEY(HouseID, ApartmentNumber));
我使用PostgreSQL。