Classic sql statements implement modification, addition, deletion, and judgment of table fields

create database test1
use test1
create table admin
(
   id int primary key ,
   name varchar(50),
   pwd  varchar(50),
)
insert into admin values(1,'aa','aa')
alter  table   admin   add   tel  varchar(50)   NULL
select * from admin

select * from admin
if   exists   (select   *   from   syscolumns   where   id=object_id('admin')   and   name='mms')   print   '已经存在该字段'
alter  table   admin   add   tel  varchar(50)   NULL

alter table admin alter column name set bbs varchar(50) null
alter table tablename  drop column oldfield

EXEC sp_rename 'admin.sss', 'tel', 'COLUMN'

本文来自CSDN博客，转载请标明出处：http://blog.csdn.net/hahahashiwo/archive/2009/12/21/5046660.aspx
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