Postgresql 分组列的平均值
我的桌子是这样的Postgresql 分组列的平均值,postgresql,Postgresql,我的桌子是这样的 id ...... amount...........food +++++++++++++++++++++++++++++++++++++ 1 ........ 5 ............. banana 1 ........ 4 ............. strawberry 2 ........ 2 ............. banana 2 ........ 7 ............. orange 2 ........ 8 ..........
id ...... amount...........food
+++++++++++++++++++++++++++++++++++++
1 ........ 5 ............. banana
1 ........ 4 ............. strawberry
2 ........ 2 ............. banana
2 ........ 7 ............. orange
2 ........ 8 ............. strawberry
3 ........ 10 .............lime
3 ........ 12 .............banana
我想要的是一个表格显示每种食物,以及它在每个ID中出现的平均次数
这张桌子应该是这样的,我想:
food ........... avg............
++++++++++++++++++++++++++++++++
banana .......... 6.3 ............
strawberry ...... 6 ............
orange .......... 7 ............
lime ............ 10 ............
我真的不知道该怎么做。如果我只使用平均值(amount),那么它只会添加整个amount列您是否尝试了
分组依据
SELECT food, AVG(amount) "avg"
FROM table1
GROUP BY food
这是
输出:
| food | avg |
|------------|-------------------|
| lime | 10 |
| orange | 7 |
| strawberry | 6 |
| banana | 6.333333333333333 |
|食品|平均值|
|------------|-------------------|
|石灰| 10|
|橙色| 7|
|草莓6|
|香蕉| 6.333|
您是否尝试了分组方式
SELECT food, AVG(amount) "avg"
FROM table1
GROUP BY food
这是
输出:
| food | avg |
|------------|-------------------|
| lime | 10 |
| orange | 7 |
| strawberry | 6 |
| banana | 6.333333333333333 |
|食品|平均值|
|------------|-------------------|
|石灰| 10|
|橙色| 7|
|草莓6|
|香蕉| 6.333|