标签:DepartmentIDnew 表之 DepartmentID Department TABLE NULL ALTER
--创建表
IF OBJECT_ID('Department','U') IS NOT NULL DROP TABLE Department
CREATE TABLE Department
(
DepartmentID smallint IDENTITY(1,1) NOT NULL,
Name NVARCHAR(20) NOT NULL,
GroupName NVARCHAR(20) NOT NULL,
CONSTRAINT PK_Department_DepartmentID PRIMARY KEY(DepartmentID)
);
--插入两条记录
INSERT INTO Department(Name,GroupName) VALUES('A','帅哥');
INSERT INTO Department(Name,GroupName) VALUES('B','美女');
--查询记录
SELECT * FROM Department
结果:
A:插入新列
ALTER TABLE Department--添加列
ADD DepartmentIDnew smallint NULL
--修改列DepartmentIDnew的值
UPDATE Department SET DepartmentIDnew=DepartmentID
B:删除主键列
--删除列需要先删除其约束
ALTER TABLE Department
DROP CONSTRAINT PK_Department_DepartmentID--删除主键
--删除列
ALTER TABLE Department
DROP COLUMN DepartmentID
结果:主键列已经被删除
C:给列增加约束
--修改列定义
ALTER TABLE Department
ALTER COLUMN DepartmentIDnew smallint NOT NULL
--给列添加约束(这里是增加主键)
ALTER TABLE Department
ADD CONSTRAINT PK_Department_DepartmentIDnew
PRIMARY KEY(DepartmentIDnew)
D:启用或禁用约束
--添加CHECK约束
ALTER TABLE Department
ADD CONSTRAINT CK_Department_DepartmentID
CHECK(DepartmentIDnew>=1)
--禁用CHECK约束
ALTER TABLE Department
NOCHECK CONSTRAINT CK_DePARTMENT_DepartmentID
--启用CHECK约束
ALTER TABLE Department
CHECK CONSTRAINT CK_Department_DepartmentID
标签:DepartmentIDnew,表之,DepartmentID,Department,TABLE,NULL,ALTER 来源: https://blog.csdn.net/ilovetheworld/article/details/94741938
本站声明: 1. iCode9 技术分享网(下文简称本站)提供的所有内容,仅供技术学习、探讨和分享; 2. 关于本站的所有留言、评论、转载及引用,纯属内容发起人的个人观点,与本站观点和立场无关; 3. 关于本站的所有言论和文字,纯属内容发起人的个人观点,与本站观点和立场无关; 4. 本站文章均是网友提供,不完全保证技术分享内容的完整性、准确性、时效性、风险性和版权归属;如您发现该文章侵犯了您的权益,可联系我们第一时间进行删除; 5. 本站为非盈利性的个人网站,所有内容不会用来进行牟利,也不会利用任何形式的广告来间接获益,纯粹是为了广大技术爱好者提供技术内容和技术思想的分享性交流网站。