1.首先創(chuàng)建一客戶張表

?

IF OBJECT_ID('dbo.Employees', 'U') IS NOT NULL

? DROP TABLE dbo.Employees;

CREATE TABLE dbo.Employees

(

? empid? ? ?INT? ? ? ? ?NOT NULL,

? firstname VARCHAR(30) NOT NULL,

? lastname? VARCHAR(30) NOT NULL,

? hiredate? DATE? ? ? ? NOT NULL,

? mgrid? ? ?INT? ? ? ? ?NULL,

? ssn? ? ? ?VARCHAR(20) NOT NULL,

? salary? ? MONEY? ? ? ?NOT NULL

);

2.主鍵約束

-- Primary key

ALTER TABLE dbo.Employees

? ADD CONSTRAINT PK_Employees

? PRIMARY KEY(empid);

??

對于主鍵約束后臺將創(chuàng)建一個唯一索引，以物理機制強制邏輯的唯一性約束

3.唯一約束

-- Unique

ALTER TABLE dbo.Employees

? ADD CONSTRAINT UNQ_Employees_ssn

? UNIQUE(ssn);

4.外鍵約束 創(chuàng)建一張訂單表 插入外鍵

IF OBJECT_ID('dbo.Orders', 'U') IS NOT NULL

? DROP TABLE dbo.Orders;

CREATE TABLE dbo.Orders

(

? orderid? ?INT? ? ? ? ?NOT NULL,

? empid? ? ?INT? ? ? ? ?NOT NULL,

? custid? ? VARCHAR(10) NOT NULL,

? orderts? ?DATETIME2? ?NOT NULL,

? qty? ? ? ?INT? ? ? ? ?NOT NULL,

? CONSTRAINT PK_Orders

? ? PRIMARY KEY(orderid)

);

-- Foreign keys

ALTER TABLE dbo.Orders

? ADD CONSTRAINT FK_Orders_Employees

? FOREIGN KEY(empid)

? REFERENCES dbo.Employees(empid);

5.CHECK約束

-- Check

ALTER TABLE dbo.Employees

? ADD CONSTRAINT CHK_Employees_salary

? CHECK(salary > 0.00);

6.默認約束

-- Default

ALTER TABLE dbo.Orders

? ADD CONSTRAINT DFT_Orders_orderts

? DEFAULT(SYSDATETIME()) FOR orderts;

-- Cleanup

DROP TABLE dbo.Orders, dbo.Employees;

總結(jié)

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