三表数据查询
三个表: 
 a表,字段UserID 
 b表,字段UserID和organizationID 
 c表,字段organizationID和organizationName   
 现想从userID知道该UserID相应的organizationName 
 该如何写存储?要效率高一些. 
------解决方案--------------------SELECT    c.organizationName 
 FROM      a INNER JOIN b 
 ON        a.UserID = b.UserID 
 INNER JOIN c 
 ON        b.organizationID = c.organizationID 
------解决方案--------------------实际上,只需对表b和表a进行内连接就可以查询了,因为要找出organizationName,就必须知道该organizationName对应的organizationID,而每个organizationID又对应一个UserID,所以, 
 select b.userid,c.organizationName 
 from b inner join c on b.organizationID=c.organizationID