求条语句
表:a 
 字段:id,cname     
 declare   @id   int 
 while(类似select   @id   =   id   from   a   where   cname   = 'xxx ') 
 begin 
 select   *   from   a   where   id   =@   id 
 end     
 ----   
 while里的语句要求判断是否有满足条件的id存在,不存在就不进入while循环,如果存在则给@id赋值,并进入循环.   
 while结构不可改变(do...while)不在考虑之列.     
------解决方案--------------------while exists (select * from a where cname= 'xxx ')