Join sql连接两个表并计算平均值
这是我的桌子 表Join sql连接两个表并计算平均值,join,ms-access-2010,average,Join,Ms Access 2010,Average,这是我的桌子 表业务 BUSINESSUSERNAME | BUSINESSPASSWORD | BUSINESSNAME| Res1 | 123 |咖啡厅| Res2 | 456 | Foodtruck | 表用户 USERNAME | USERPASSWORD | NAME| 用户1 | 123 |先生1| 用户2 | 234 |先生2 | 表食品 FOODID|FOODNAME|FOODPRICE|BUSINESSUSERNAME| 1 |CAKE | 5 |Re
业务
BUSINESSUSERNAME | BUSINESSPASSWORD | BUSINESSNAME|
Res1 | 123 |咖啡厅|
Res2 | 456 | Foodtruck |
表用户
USERNAME | USERPASSWORD | NAME|
用户1 | 123 |先生1|
用户2 | 234 |先生2 |
表食品
FOODID|FOODNAME|FOODPRICE|BUSINESSUSERNAME|
1 |CAKE | 5 |Res1 |
2 |SHAKE | 2 |Res2 |
3 |COLA | 3 |Res1 |
表食品评级
FOODREVIEWID|FOODID|FOORATING|BUSINESSUSERNAME|USERNAME|
1 |2 |3 |Res2 |user1 |
2 |2 |5 |Res2 |user2 |
3 |1 |4 |Res1 |user1 |
4 |3 |1 |Res1 |user1 |
我想要这张桌子
其中BUSINESSUSERNAME=“Res1”
查询
select f.foodname, f.foodprice, avg(fr.foodrating)
from food_rating fr
inner join food f
on fr.foodid = f.foodid
group by f.foodname, f.foodprice
;
输出
+----------+-----------+--------------------+
| FOODNAME | FOODPRICE | avg(fr.foodrating) |
+----------+-----------+--------------------+
| CAKE | 5 | 4 |
| SHAKE | 2 | 4 |
+----------+-----------+--------------------+
我有此代码,但我无法找到工作地点选择食物。食物名称,食物。食物价格,圆形(平均值(食物价格),1)作为食物从食物左侧开始加入食物\u关于食物的评论。FOODID=FOOD\u REVIEW.FOODID按食物分组。FOODNAME,FOOD.FOODPRICE where BUSINESSUSERNAME=“something您缺少something
后面的尾端引号。但是你的结构很奇怪。为什么要在两个表中都存储businessusername?我有4个表,分别是BUSINESS、USER、FOOD、FOOD\u REVIEW businessusername是我在表BUSINESS中的主键,我在查询表达式'FOOD.FOODPRICE where businessusername=“something”中遇到了“语法错误(缺少运算符)”,请将此信息编辑回问题中(并确认您使用的dbms)。还为所有涉及的表添加表结构选择FOOD.FOODNAME,FOOD.FOODPRICE,ROUND(AVG(FOODRATING),1)作为FOODAVGRATING FROM FOOD LEFT JOIN FOOD_REVIEW ON FOOD.FOODID=FOOD_REVIEW.FOODID WHERE FOOD.BUSINESSUSERNAME=“LCpak”GROUP BY FOOD.FOODNAME,FOOD.FOODPRICEpick one(mysql,sqlserver,msaccess)。此外,为什么businessusername同时存储在食品和食品评级中?这可能需要重新建模
+----------+-----------+--------------------+
| FOODNAME | FOODPRICE | avg(fr.foodrating) |
+----------+-----------+--------------------+
| CAKE | 5 | 4 |
| SHAKE | 2 | 4 |
+----------+-----------+--------------------+