MATCH（somefeald）AGAINST（'+“。$ _ GET ['search']。''在BOOLEAN MODE中）不起作用

Question

select
 webs.title,webs.disc,webs.logo,webs.id
from 
 webs
 JOIN rel ON rel.webid=webs.id
 JOIN catagory on catagory.id=rel.catid 
where 
  webs.app!=0 
  AND MATCH (webs.title,webs.city,webs.state,webs.url,catagory.catname) AGAINST ('+".$_GET['search']."' IN BOOLEAN MODE)

此查询给出空白结果，但

SELECT * FROM webs 
   WHERE MATCH (title,city,state,url) AGAINST ('+".$_GET['search']."' IN BOOLEAN MODE)"; 

给出结果，但我必须使用JOIN作为我的代码，任何解决方案？