sql - SQL显示行中数据的总和

Question

我有一张这样的桌子

No.
--
b
r
g
g
r
b
r
g

我想要如下结果集

Type of color | Ocurrence
Blue              2
green             3
red               3
TOTAL             8

请帮忙

Answer 1

听起来像CASE并且GROUP BY将是您所需要的；

SELECT 
  CASE WHEN color = 'r' THEN 'red' 
       WHEN color = 'g' THEN 'green'
       WHEN color = 'b' THEN 'blue'
  END "Type of color", COUNT(color) "Occurrence"
FROM Table1
GROUP BY color
ORDER BY color;

一个用于测试的 SQLfiddle。

要获得总数，一种（不一定是最简单的）方法是将 UNION 与总数合并；

WITH cte AS (
  SELECT 
    CASE WHEN color = 'r' THEN 'red' 
         WHEN color = 'g' THEN 'green'
         WHEN color = 'b' THEN 'blue'
    END "Type of color", COUNT(color) "Occurrence" 
  FROM Table1
  GROUP BY color
  UNION 
  SELECT 'TOTAL',COUNT(*) 
  FROM Table1
)
SELECT * FROM cte
ORDER BY CASE WHEN "Type of color" = 'TOTAL' THEN 1 END;

另一个 SQLfiddle。

Answer 2

Joachim 的回答很好，除了有一种更简单的方法可以使用以下方法获得总数rollup：

SELECT 
  CASE WHEN color = 'r' THEN 'red' 
       WHEN color = 'g' THEN 'green'
       WHEN color = 'b' THEN 'blue'
       when color is NULL then 'Total'
  END "Type of color", COUNT(*) "Occurrence"
FROM Table1
GROUP BY color with rollup
ORDER BY (case when color is null then 1 else 0 end), color