SQL 查询 - 使用 COUNT

Question

我有一个这样的数据库结构：

Table - lodges
LodgeID (PK)
Lodge
etc

Table - scores
ScoreID (PK)
Score
CategoryID
LodgeID (FK)

我正在尝试以以下形式返回结果：

LodgeID、Lodge、类别、该类别的分数、该类别的平均分数

例如，如果我有：

旅馆

LodgeID, Lodge
1, Lodge One
2, Lodge Two

分数

ScoreID, Score, CategoryID, LodgeID
1, 3, 101, 1
2, 5, 101, 1
3, 7, 101, 1
4, 10, 102, 2
5, 20, 102, 2
6, 30, 102, 2
7, 40, 102, 2

我想回来：

1, Lodge One, 3, 5
2, Lodge Two, 4, 25

我一直在尝试这样的事情：

SELECT        COUNT(ScoreID) as scoreCount, AVG(Score) as AverageScore, Lodge 
FROM          scores_temp 
INNER JOIN    lodges_temp ON scores_temp.LodgeID = lodges_temp.LodgeID

SELECT lodges_temp.LodgeID, Lodge, COUNT(ScoreID) as scoreCount, AVG(Score) as AverageScore FROM lodges_temp INNER JOIN scores_temp ON lodges_temp.LodgeID = scores_temp.LodgeID

没有任何成功。任何指针将不胜感激。

Answer 1

试试这个

SELECT        COUNT(ScoreID) as scoreCount, AVG(Score) as AverageScore, Lodge 
FROM          scores_temp 
INNER JOIN    lodges_temp ON scores_temp.LodgeID = lodges_temp.LodgeID
GROUP BY Lodge

Answer 2

您缺少group by 子句：

SELECT     COUNT(ScoreID) as scoreCount, AVG(Score) as AverageScore, Lodge 
FROM       scores
INNER JOIN lodges ON scores.LodgeID = lodges.LodgeID
GROUP BY   lodge