mysql得到重複行使用哪裏

Question

pid fid 
6 19 
7 19 
8 19 
9 19 
7 30 
6 30 

我有一個這樣的表。我想選擇重複行， 當我送19，30個IDS使用的IN條款，如：

Select pid from tablename where fid IN (19,30); 

我想這些結果

pid 
7 
6 

是否有任何MySQL的語句來得到這些結果？

Answer 1

使用distinct

Select distinct pid from tablename where fid IN (19,30); 

或者找到重複

select pid from tablename group by fid having count(*)>1 

Answer 2

SELECT pid 
FROM tableName 
WHERE fid IN (19,30) 
GROUP BY pid 
HAVING COUNT(*) = 2 

如果唯一約束是不fid每個pid定義，那麼你需要有DISTINCT內COUNT

SELECT pid 
FROM tableName 
WHERE fid IN (19,30) 
GROUP BY pid 
HAVING COUNT(DISTINCT fid) = 2 

• SQLFiddle Demo

Answer 3

SELECT 
    pid 
FROM tablename 
where fid IN (19,30) 
group by 
pid 

Answer 4

首先，你應該組PID的並計數，然後拿那些與多個occurence

SELECT pid, count(*) AS cnt 
FROM tablename 
WHERE fid IN (19,30) 
GROUP BY pid 
HAVING cnt > 1