SQL语法基础
--创建表的同时创建约束
use tempdb
if Object_ID('testDB') is not Null
drop table testDB;
CREATE TABLE testDB(
ID INT IDENTITY(1,1) NOT NULL,
[Name] NVARCHAR(50) NOT NULL ,
Description NVARCHAR(2000) NOT NULL,
CreateDate Datetime Default(getDate()),
CONSTRAINT PK_ID PRIMARY KEY CLUSTERED (ID ASC),
CONSTRAINT CHK_ID Check (ID between 1 and 1000)
)
--删除约束
use tempdb
alter Table testDB Drop Constraint PK_ID
--修改约束
use tempdb
alter Table testDB Add Constraint PK_ID Primary key CLUSTERED(ID ASC)
1:约束格式
CONSTRAINT Constraint_name Constraint_type(col)
Constraint_type:check,Primary key,Foreign key,unique