SQL如何Count Distinct過的資料
阿新 • • 發佈：2019-01-26
distinct:
<pre name="code" class="sql">SELECT distinct t1.*,t2.industryId FROM positions t1 ,planteddetails t2, landplanted t3 where t3.landId = t1.id and t2.plantedId = t3.id
and (t1.landType like '%糧%' or t1.gatherId like '%糧%') and t2.industryId ='1'直接count會報錯
SELECT count((distinct t1.*,t2.industryId FROM positions t1 ,planteddetails t2, landplanted t3) where t3.landId = t1.id and t2.plantedId = t3.id and (t1.landType like '%糧%' or t1.gatherId like '%糧%') and t2.industryId ='1'
所以我們可以換個思路
select count(*) from (SELECT distinct t1.*,t2.industryId FROM positions t1 ,planteddetails t2, landplanted t3 where t3.landId = t1.id and t2.plantedId = t3.id
and (t1.landType like '%糧%' or t1.gatherId like '%糧%') and t2.industryId ='1') as total直接把distinct的結果作為一張表count
這裡as total是必須的 臨時表需要名字 不然會報錯