親測有效。代碼如下:
select a.id from app a
left join (select uid,id,name from weixin group by uid) b on a.id=b.uid
如上代碼段所示,依據uid判斷重複的記錄,group by ,只顯示一條記錄。
若是group by查詢較慢,也可這樣寫,在group by之前增加一個where條件,速度馬上就上來。
select a.id from app a
left join (select uid,id,name from weixin where 索引條件 group by uid) b on a.id=b.uid