--修改表名

--格式：SP_RENAME TABLENAME,NEWTABLENAME

SP_RENAME TABLENAME,NEWTABLENAME

--只能对表，不能对临时表

--修改字段名

--格式：SP_RENAME 'TABLENAME.COLNAME',NEWCOLNAME,'COLUMN'

SP_RENAME 'TABLENAME.COLNAME',NEWCOLNAME,'COLUMN'

--添加字段

--格式：ALTER TABLE TABLE_NAME ADD NEW_COLUMN DATA_TYPE [INTERALITY_CODITION]

示例1

ALTER TABLE STUDENT ADD NATIONALITY VARCHAR(20)

ALTER TABLE STUDENT ADD ID IDENTITY INT(1,1)

--示例2 添加INT类型的列,默认值为 0

ALTER TABLE STUDENT ADD STUDENTNAME INT DEFAULT 0

--示例3 添加INT类型的列,默认值为0，主键

ALTER TABLE STUDENT ADD STUDENTID INT PRIMARY KEY DEFAULT 0 

--示例4 判断STUDENT中是否存在NAME字段且删除字段

IF EXISTS(SELECT * FROM SYSCOLUMNS WHERE ID=OBJECT_ID('STUDENT') AND NAME='NAME') BEGIN

ALTER TABLE STUDENT DROP COLUMN NAME

END

更改字段

格式：ALTER TABLE TABLE_NAME ALTER COLUMN COLUMN_NAME

ALTER TABLE STUDENT ALTER COLUMN NAME VARCHAR(200)

删除字段

格式：ALTER TABLE TABLE_NAME DROP COLUMN COLUMN_NAME

ALTER TABLE STUDENT DROP COLUMN NATIONALITY;

查看字段约束

格式： SELECT * FROM INFORMATION_SCHEMA.CONSTRAINT_COLUMN_USAGE WHERE TABLE_NAME = TABLE_NAME

SELECT TABLE_NAME,COLUMN_NAME,CONSTRAINT_NAME FROM INFORMATION_SCHEMA.CONSTRAINT_COLUMN_USAGE

WHERE TABLE_NAME = 'STUDENT'

查看字段缺省约束表达式 （即默认值等）

格式：SELECT * FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME = TABLE_NAME

SELECT TABLE_NAME, COLUMN_NAME, COLUMN_DEFAULT FROM INFORMATION_SCHEMA.COLUMNS

WHERE TABLE_NAME='STUDENT'

查看字段缺省约束名

格式：SELECT NAME FROM SYSOBJECTS WHERE OBJECT_ID(TABLE_NAME)=PARENT_OBJ AND XTYPE=’D’

SELECT NAME FROM SYSOBJECTS

WHERE OBJECT_ID('表?名?')=PARENT_OBJ AND XTYPE='D'

删除字段约束

格式：ALTER TABLE TABLENAME DROP CONSTRAINT CONSTRAINTNAME

ALTER TABLE STUDENT DROP CONSTRAINT PK__STUDENT__2F36BC5B772B9A0B

添加字段约束

格式：ALTER TABLE TABLENAME ADD CONSTRAINT CONSTRAINTNAME PRIMARY KEY (COLUMN_NAME)

--示例1

ALTER TABLE STUINFO ADD CONSTRAINT PK_STUNO PRIMARY KEY (STUNO)

--示例2 添加主键约束（PRIMARY KEY）

-- 存在主键约束PK_STUNO，则删除

IF EXISTS(SELECT * FROM SYSOBJECTS WHERE NAME='PK_STUNO' AND XTYPE='PK')

ALTER TABLE STUINFO

DROP CONSTRAINT PK_STUNO

GO

-- 重新添加主键约束PK_STUNO

ALTER TABLE STUINFO ADD CONSTRAINT PK_STUNO PRIMARY KEY (STUNO)

GO

--示例3 添加 唯一UQ约束（UNIQUE CONSTRAINT）

-- 存在唯一约束UQ_STUNO，则删除

IF EXISTS(SELECT * FROM SYSOBJECTS WHERE NAME='UQ_STUID' AND XTYPE='UQ')

ALTER TABLE STUINFO

DROP CONSTRAINT UQ_STUID

GO

-- 重新添加唯一约束UQ_STUID

ALTER TABLE STUINFO ADD CONSTRAINT UQ_STUID UNIQUE (STUID)

--示例4 添加默认DF约束（DEFAULT CONSTRAINT）

-- 存在默认约束UQ_STUNO，则删除

IF EXISTS(SELECT * FROM SYSOBJECTS WHERE NAME='DF_STUADDRESS' AND XTYPE='D')

ALTER TABLE STUINFO DROP CONSTRAINT DF_STUADDRESS

GO

-- 重新添加默认约束DF_STUADDRESS

ALTER TABLE STUINFO ADD CONSTRAINT DF_STUADDRESS DEFAULT ('地址不详') FOR STUADDRESS

--示例5 检查CK约束（CHECK CONSTRAINT）

-- 存在检查约束UQ_STUNO，则删除

IF EXISTS(SELECT * FROM SYSOBJECTS WHERE NAME='CK_STUAGE' AND XTYPE='C')

ALTER TABLE STUINFO DROP CONS