如何将不同查询的结果合二为一？

Question

我在一列中有情绪分析的结果。我想显示每个数字代表什么以及计数，如下所示：

 Neg | Neutral | Pos 
---------+-----+-----
  30 |   55    | 100 

我尝试了许多在互联网上找到的不同方法，但均无济于事。 db2 语法似乎经常更改，并且我找到的所有文档都不适用于我当前的 bluemix 帐户。

我能得到的最接近的是 UNION：

SELECT  COUNT(*) as NEGATIVE      FROM C7  WHERE SENTIMENT = 1
union
SELECT  COUNT(*) as NEUTRAL       FROM C7  WHERE SENTIMENT = 2
union
SELECT  COUNT(*) as Pos           FROM C7  WHERE SENTIMENT = 3

但是，这给了我：

NEGATIVE
--------
   30
   55
  100

如何并排合并每个查询的结果？

---

我尝试了 Pivoting in DB2 帖子中的答案，但出现错误：

SELECT 
  C7.SENTIMENT,
  COUNT(CASE WHEN C7.SENTIMENT = 1 THEN Value END) AS NEGATIVE,
  COUNT(CASE WHEN C7.SENTIMENT = 2 THEN Value END) AS NEUTRAL,
  COUNT(CASE WHEN C7.SENTIMENT = 3 THEN Value END) AS POSITIVE,
FROM C7
GROUP BY C7.SENTIMENT

SQL0206N: SQL0206N “VALUE”在使用它的上下文中无效。 SQLSTATE=42703

SELECT DISTINCT
  C7.SENTIMENT,
    (SELECT value  FROM C7  WHERE C7.SENTIMENT = 1) AS VERY_NEGATIVE,
    (SELECT value  FROM C7  WHERE C7.SENTIMENT = 2) AS NEGATIVE,
    (SELECT value  FROM C7  WHERE C7.SENTIMENT = 3) AS NEUTRAL
FROM C7

SQL0206N: SQL0206N “VALUE”在使用它的上下文中无效。 SQLSTATE=42703

Answer 1

好的，所以在修改了一些答案之后，我终于得到了我想要的东西：

SELECT DISTINCT
  (SELECT COUNT(SENTIMENT) FROM C7 WHERE C7.SENTIMENT = 1) AS NEGATIVE,
  (SELECT COUNT(SENTIMENT) FROM C7 WHERE C7.SENTIMENT = 2) AS NEUTRAL,
  (SELECT COUNT(SENTIMENT) FROM C7 WHERE C7.SENTIMENT = 3) AS POSITIVE
FROM C7

这似乎是我徘徊了很长时间，但找不到，因为有些帖子用奇怪的表名和值回答了这个问题。

所以基本上，要让查询彼此相邻，您必须使用多个SELECTs。

另外，请注意我使用了DISTINCT，否则它会为我的数据库中的每一行提供相同数据的副本。