子查询与聚合函数混合

时间:2018-12-11 02:07:31

标签: sql subquery aggregate-functions

我正在尝试找出此查询,这使我感到困惑。目标是创建一个要显示的SQL查询:Scholarship_Name,授予的平均金额。我将链接下面的表格以及我到目前为止所做的查询,希望有人可以指出我在做什么错。

我想指出的是,这两个表没有任何相同的PK或FK,所以这就是为什么我以自己的方式链接它们的原因。到目前为止,我在查询中所做的工作都显示了名称,但是当我尝试对数量进行平均时,它们将变为0.0。我很沮丧,整天都在搜寻。任何帮助,将不胜感激。

奖学金

ID / SCHOLARSHIP_NAME / AMOUNT_AVAILABLE

"1" "Presidents Award"  "$15,000"

"2" "Chancellor Academic Award" "$25,000"

"3" "Chevron Award" "$20,000"

SCHOLARSHIP_AWARDS

ID / SCHOLARSHIP_ID / STUDENT_ID / AMOUNT_AWARDED

"1" "2" "9" "$1,500"

"2" "3" "8" "$1,500"

"3" "1" "7" "$2,000"

"4" "2" "6" "$1,500"

"5" "2" "5" "$3,000"

"6" "3" "4" "$5,000"

"7" "3" "3" "$2,500"

"8" "2" "2" "$2,500"

"9" "1" "1" "$1,500"

查询:

SELECT Scholarships.SCHOLARSHIP_NAME, AVG(Scholarship_Awards.Amount_Awarded) AS "Average Amount Awarded"
FROM Scholarships JOIN Scholarship_Awards
ON Scholarship_Awards.SCHOLARSHIP_ID = SCHOLARSHIPS.ID
GROUP BY SCHOLARSHIP_NAME

0 个答案:

没有答案