SQL Server 中的可延迟约束

# SQL Server 中的可延迟约束及其应用

sql
-- 创建可延迟的 PRIMARY KEY 约束
ALTER TABLE TableName
ADD CONSTRAINT PK_ConstraintName PRIMARY KEY CLUSTERED (Column1, Column2) WITH (DEFERRED);

sql
-- 创建可延迟的 FOREIGN KEY 约束
ALTER TABLE ChildTable
ADD CONSTRAINT FK_ConstraintName FOREIGN KEY (ForeignKeyColumn)
REFERENCES ParentTable (PrimaryKeyColumn) WITH (DEFERRED);

sql
-- 创建可延迟的 CHECK 约束
ALTER TABLE TableName
ADD CONSTRAINT CHK_ConstraintName CHECK (Column1 > 0) WITH (DEFERRED);

sql
-- 创建订单表
CREATE TABLE Orders (
    OrderID INT PRIMARY KEY,
    CustomerName NVARCHAR(50)
);
-- 创建订单详情表
CREATE TABLE OrderDetails (
    DetailID INT PRIMARY KEY,
    OrderID INT,
    ProductName NVARCHAR(50),
    Quantity INT,
    CONSTRAINT FK_OrderDetails_Orders FOREIGN KEY (OrderID) REFERENCES Orders(OrderID) WITH (DEFERRED)
);