SQL数据库的操作（只保存最新三条记录）,该怎么解决

SQL数据库的操作（只保存最新三条记录）
请问在创建的一个表中这样让它只能添加三条记录，如表中没超过三天记录时直接添加，如果超过的三条，如第四条记录，这样去掉最早添加的，反正就是只保存最新三条记录，请问这样的SQL 语句怎么写啊？？？非常感谢你们的！！！

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SQL code

举个简单的例子declare @rowCount intselect @rowCount=COUNT(*) from tbif @rowCount<3    begin        insert into tb select GETDATE()    endelse    begin        delete from tb where updateDate =(select MIN(updateDate) from tb)        insert into tb select GETDATE()    end
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SQL code
create table tab (id int,name varchar(32))goinsert tab select 1,'sdf' union allselect 2,'aerwe' union allselect 3,'werwerf'gocreate trigger instead_tri_name on tabinstead of insertasbegin    declare @id int,@name varchar(32)    select @id=id,@name=name from inserted    declare @count int,@curr_first int    select @count=count(1) from tab    select @curr_first=id from tab    if @count=3        begin            delete from tab  where id= (select min(id) from tab)            insert tab select @id,@name        end        else        begin            insert tab select @id,@name        endend
[解决办法]
那就不创建触发器，判断以后在插入数据