select uname,count(cid) from nowday group by uname order by count(cid) desc
select uname,count(cid) from nowday where status=2 group by uname order by count(cid) desc
意思就是要查詢 用戶名，操作量，無效操作量（status=2）
如果可以的話，能在這個基礎上追加查詢一個無效操作率嗎？（無效操作量/操作量） 要求結果是百分比表示，保留兩位小數
uj5u.com熱心網友回復：
select s1.uname ,s1.youxiao,s2.wuxiao from (select uname,count(cid) youxiao from nowday group by uname )s1left join
(select uname,count(cid) wuxiao from nowday where status=2 group by uname) s2
on s1.uname = s2.uname
要是我來寫的話就是這樣的
uj5u.com熱心網友回復：
從篩選條件來看兩個陳述句回傳的結果集所滿足的條件是不一致的，所以無法直接合并，但是可以考慮對結果集進行二次合并。uj5u.com熱心網友回復：
select uname,count(cid) from nowday group by uname order by count(cid) descunion
select uname,count(cid) from nowday where status=2 group by uname order by count(cid) desc
uj5u.com熱心網友回復：
可以， 用case when， 但是比較麻煩select uname, count(cid1) as cid1, sum(cid2) as cid2 from
(select uname，1 as cid1， case when status=2 then 1 else 0 end as cid2 from nowday ) as t group by uname, order by cid1
但是合并的話， 沒辦法同時滿足兩個欄位排序
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標籤：MySQL
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