加入計數

Question

我想知道哪個播放列表中有2首以上的歌曲。該聲明有效，但我希望播放列表的名稱和顯示歌曲的count（）。我想我必須使用加入，但我沒有得到它應該如何工作。 有人可以幫忙嗎？

playlist table 
++++++++++++++ 
id 
name 

playlist_songs table 
++++++++++++++++++++ 
song_id 
playlist_id 


SELECT p.name FROM playlist p 
WHERE p.id in (SELECT s.playlist_id counter FROM playlist_songs s 
group by playlist_id 
having count(song_id)>2); 

Answer 1

我想要的播放列表的名稱和計數（）所顯示的歌曲 。

的使用JOIN在IN謂詞的優勢，這其中：

SELECT 
    p.name, 
    COUNT(song_id) counter 
FROM playlist p 
INNER JOIN playlist_songs s ON p.id = s.playlist_id 
GROUP BY playlist_id 
HAVING COUNT(song_id) > 2; 

Answer 2

嘗試： -

SELECT 
    p.name, 
    count(s.song_id) 
FROM 
    playlist p 
INNER JOIN 
    playlist_songs s 
ON 
    p.id = s.playlist_id 
GROUP BY 
    p.name 
HAVING 
    COUNT(s.song_id) >= 2 

這是SQL服務器的語法，但應該在甲骨文工作。

Answer 3

這是你所需要的：

SELECT p.name as name, count(*) as counter 
FROM playlist p left outer join playlist_songs s on (p.id = s.playlist_id) 
GROUP BY p.name 
HAVING count(*) > 2 

Answer 4

請嘗試：

SELECT a.name 
FROM 
    playlist a INNER JOIN playlist_songs b 
    ON a.id = b.playlist_id 
GROUP BY a.name 
HAVING COUNT(*) >1 

Answer 5

始終使用如果可能的話

SELECT p.name play_list,count(s.song_id) total_songs 
FROM playlist p 
INNER JOIN playlist_songs s 
ON p.id = s.playlist_id 
GROUP BY p.name 
HAVING COUNT(s.song_id) >= 2;