http://blog.****.net/wuxiaokaixinguo/article/details/8293048
检查数据库中是否存在某个表，不存在则生成该表
方法一：
IF NOT EXISTS (select * from dbo.sysobjects where xtype='U' and Name = 'T_Users')
BEGIN
CREATE TABLE [dbo].[T_Users](userName varchar(20),userPass varchar(20));
END
方法二：
create procedure sel_tab
@table_name varchar(20)
AS
declare @flag int
set @flag=0;
set @flag = (select flag from (select count(*) as flag from dbo.sysobjects where xtype='U' and Name = 'T_Users') as sel_count);
if @flag = 0
create table T_Users(userName varchar(20),userPass varchar(20));
GO
EXEC sel_tab "T_Users"
判断列是否存在
if not exists(select * from syscolumns where id=object_id('TPARTNER') and name='AgencyPCC')
begin
alter table dbo.TPARTNER add AgencyPCC nvarchar(50) null
End
GO
select AgencyPCC,* from dbo.TPARTNER;
if exists(select * from syscolumns where id=object_id('TPARTNER') and name='AgencyPCC')
begin
alter table dbo.TPARTNER drop COLUMN AgencyPCC
End
Create Table table1(ID Int)
GO
if not exists (select Name From SysColumns Where ID = OBJECT_ID('table1') And Name = 'New_column')
ALTER TABLE table1 ADD New_column VARCHAR(20) NULL
GO
Select * From table1
GO
Drop Table table1
--Result
/*
ID New_column