那些臭名昭著的sql

* from a, b left join c on b.id = c.id left join d on c.id = d.id 多表关联查询，where条件使用各种函数，导致索引无效。数据量如果打起来以后会导致查询像蜗牛一样。

 select   
trim(d.circuitid)   as   circuitid,
trim(d.Code)   as   Code,
trim(d.Oldname)   as   Oldname,
trim(d.Circuittype)   as   Circuittype,
trim(d.Status)   as   Status,
trim(d.customerid)   as   acustomerid,
trim(d.alinkman)   as   alinkman,
trim(d.zlinkman)   as   zlinkman,
trim(d.alinkmantel)   as   alinkmantel,
trim(d.zlinkmantel)   as   zlinkmantel,
trim(d.busi_no)   as   busi_no,
trim(d.service_serial)   as   service_serial,
trim(a.region_ID)   as   regionid ,
  2   as   SORTID
  from   test1 a,test2 b,test3 c,test4 d 
  where  trim(a.room_id) = trim(b.roomID)  and  trim(b.neid) = trim(c.neid)  and  (trim(c.portid) = trim(d.aendname)  or  trim(c.portid) = trim(d.zendname))

 

那些臭名昭著的sql

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