SQL 根据其他列的条件进行平均计算

Question

如何根据其他列的条件输出一列的平均值？例如，这是我所做的：

SELECT  
    AVG(TestScores WHERE ID = 1 AND Date_On BETWEEN '2017-04-08' AND '2017-04-12' AND Code = '87A')    
FROM
    Table_Name

我想要的目标是在 row = 1 的 ID 和日期落在我指定的时间间隔之间时获得 TestScores 列的平均值。这可能吗？

Answer 1

如果您在 Sql 服务器上，那么以下是您要查找的内容（我认为）：

SELECT 
    AVG(TestScores)   
FROM
    Table_Name
WHERE ID = 1 
    AND Date_On BETWEEN '2017-04-08' AND '2017-04-12' 
    AND Code = '87A'

EDIT, as per comments underneath:

SELECT 
    ID,
    AVG(TestScores)   
FROM
    Table_Name
WHERE 
    Date_On BETWEEN '2017-04-08' AND '2017-04-12' 
    AND Code = '87A'
GROUP BY ID

Answer 2

这里是查询：-

SELECT  AVG(TestScores)    
FROM  Table_Name 
WHERE ID = 1 AND
Date_On BETWEEN '2017-04-08' AND '2017-04-12' AND Code = '87A'

SQL Average Calculation based on conditions of other columns