postgres union結果の集約

Question

postgres DB内の単一のテーブルを使用して、SQLで日付ごとに結果の行を取得しようとしています。私はユニオンを使ってみましたが、これは正しい方法ではないと思います。私は正しいSQLを構築するのに役立ちますか？

表のコンテンツのためのサンプルデータ列：ID、のCreationDate、使用している場合

1 |2016-04-02|PAGE 
2 |2016-04-02|ATTACHMENT 
3 |2016-04-02|PAGE 
4 |2016-04-03|ATTACHMENT 
5 |2016-04-03|PAGE 
6 |2016-04-03|ATTACHMENT 
7 |2016-04-03|PAGE 
8 |2016-04-04|ATTACHMENT 
9 |2016-04-04|ATTACHMENT 
10|2016-04-04|ATTACHMENT 

をCONTENTTYPEこのSQLクエリ：

SELECT 
    date(creationdate) AS create_date, 
    COUNT(*) AS PAGE,0 AS ATTACHMENT 
FROM 
    content 
WHERE 
    contenttype='PAGE' GROUP BY content.creationdate 
UNION 
SELECT 
    date(creationdate) AS create_date, 
    0 AS PAGE,COUNT(*) AS ATTACHMENT 
FROM 
    content 
WHERE 
    contenttype='ATTACHMENT' GROUP BY content.creationdate 
ORDER BY create_date ASC; 

私は私が欲しい結果に

|create_date|PAGE|ATTACHMENT| 
|2016-04-02|0|2| 
|2016-04-02|1|0| 
|2016-04-03|0|2| 
|2016-04-03|1|0| 
|2016-04-04|3|0| 

を取得は：

|create_date|PAGE|ATTACHMENT| 
|2016-04-02|1|2| 
|2016-04-03|2|2| 
|2016-04-04|3|0| 

Answer 1

あなたは一度だけのテーブルから選択することで、条件付き集計でそれを行うことができます。

SELECT date(creationdate) AS create_date, 
     count(CASE WHEN contenttype='PAGE' then 1 end) as PAGE, 
     count(CASE WHEN contenttype='ATTACHMENT' then 1 end) as ATTACHMENT 
FROM 
    content 
GROUP BY content.creationdate 
ORDER BY create_date ASC; 

Answer 2

あなたは条件付き集計が必要になります。

SELECT 
    date(creationdate) AS create_date, 
    SUM(CASE WHEN contenttype='PAGE' THEN 1 ELSE 0 END) AS PAGE, 
    SUM(CASE WHEN contenttype='ATTACHMENT' THEN 1 ELSE 0 END) AS ATTACHMENT 
FROM 
    content 
GROUP BY content.creationdate 
ORDER BY create_date ASC; 

Answer 3

、いくつかの方法：

SELECT date(c.creationdate) AS create_date, 
p p_count,a_count 
FROM 
(SELECT DISTINCT creationdate FROM content) c INNER JOIN (SELECT creationdate,count() p_count FROM CONTENT GROUP 
BY creationdate,contenttype HAVING contenttype='PAGE') p on p.creationdate=c.creationdate 
INNER JOIN (SELECT creationdate,count() a_count FROM CONTENT GROUP 
BY creationdate,contenttype HAVING contenttype='ATTACHMENT') p 
ON p.creationdate=c.creationdate ORDER BY c.creationdate 

これはこれです