sqlserver常用操作——判断关键字段是否重复插入记录

sqlserver常用操作（2）——判断关键字段是否重复插入记录

插入数据，判断这条数据是否重复，游标中采用的思想是逐条循环判断是否添加。
方法一：
insert into
dbo.News (NewsTitle,Typeid,TypeName,[content])
select NewsTitle,[content]
from dbo.News2 b
where b.NewsTitle not in(select  NewsTitle from dbo.News)

方法二：
insert into
dbo.News (NewsTitle,[content]
from dbo.News2 b
where not exists
(select * from dbo.news where NewsTitle=b.NewsTitle)

游标操作示例一：
declare   @cur_pos   int  
declare   mycursor   cursor   for   select   NewsTitle,Typeid   from   dbo.News  
declare   @col1   char(10)  
declare   @col2   char(10)    
open   mycursor  
fetch next from mycursor   into   @col1,@col2  
while   @@fetch_status<>-1  
begin  
print @col1+@col2
--select   @cur_pos=@cur_pos+1  
fetch next from  mycursor   into   @col1,@col2  
end  
close mycursor
deallocate mycursor

游标操作示例二：
declare @cur_pos int
declare @newsid int
declare @newstitle varchar(20)
declare mycursor cursor for select Newsid,NewsTitle from dbo.News2

open mycursor
fetch next from mycursor into @newsid,@newstitle
while @@fetch_status<>-1
begin
if not exists
(select * from dbo.News where NewsTitle=@newstitle)
    begin
    insert into dbo.News(NewsTitle,[content])
    select NewsTitle,[content]
    from dbo.News2 where NewsId=@newsid
    end
fetch next from mycursor into @newsid,@newstitle
end

close mycursor
deallocate mycursor

转自： http://www.thaught.cn/go.php/category/16/1/2/