如何在一個查詢中得到不同條件下的總和？

Question

如何做到以下幾點在一個查詢：

如果我有兩個疑問這樣的

SELECT SUM(value +sal) AS sump 
FROM loans 
WHERE active_flag = 1 

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SELECT SUM(value +sal) AS sumn 
FROM loans 
WHERE active_flag = 2 

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我想sump和sumn在同一查詢

Answer 1

SELECT SUM(CASE 
      WHEN active_flag = 1 THEN value + sal 
      ELSE 0 
      END) AS sump, 
     SUM(CASE 
      WHEN active_flag = 2 THEN value + sal 
      ELSE 0 
      END) AS sumn 
FROM loans 
WHERE active_flag IN (1, 2)