在查询中使用特定的count（）函数。

SELECT name as `Candidate Name`, 
    COUNT(CASE WHEN sentiment='Negative' THEN 1 END) AS `Negative`,
    COUNT(CASE WHEN sentiment='Positive' THEN 1 END) AS `Positive`,
    COUNT(CASE WHEN sentiment='Neutral' THEN 1 END) AS `Neutral`,
    COUNT(*) AS `Total`

FROM [table]

GROUP BY candidate

我喜欢用if（）或case when来解决这类问题。轴心点有时很费时思考。

SELECT
  Name as CandidateName,
  SUM(IF(Sentiment = 'N', 1, 0)) as Negative,
  SUM(IF(Sentiment = 'Y', 1, 0)) as Positive,
  SUM(IF(Sentiment = 'N', 1, 0)) as Neutral
  COUNT(*) as Total
FROM [TABLE]
GROUP BY
  Name

要使用t-sql，或者只使用case when，相同的代码可能如下所示：

SELECT
  Name as CandidateName,
  SUM(CASE WHEN Sentiment = 'N' THEN 1 ELSE 0 END) as Negative,
  SUM(CASE WHEN Sentiment = 'Y' THEN 1 ELSE 0 END) as Positive,
  SUM(CASE WHEN Sentiment = 'N' THEN 1 ELSE 0 END) as Neutral
  COUNT(*) as Total
FROM [TABLE]
GROUP BY
  Name