在一张表中基于第二个字段获取一个字段的MAX值

Question

我有2个桌子“房间”和“建筑物”

我正在尝试按建筑物名称分组获得最大“房间总价” AS“总建筑物价”。 我知道应该有一个子查询来从roomPrice获取值，因此max（roomprice）可以工作，但我无法正确地做到这一点。

Table1 ( roomNo, buildingNo, roomType, roomPrice )
Table2 ( buildingNo, buldingName, buildingCity )

抱歉，SQL才刚刚开始，书还没有全部介绍。

Answer 1

尝试这种方式：

select a.buildingNo,b.buildingName,b.buildingCity ,a.max_room_price from
(select buildingNo,max(roomPrice) as max_room_price from table1 GROUP BY buildingNo) as a

LEFT JOIN
(select buildingNo, buildingName,buildingCity from table2)as b
on a.buildingNo = b. buildingNo

根据您想要的输出，这一项工作正常。 希望能帮助到你

Answer 2

也尝试一下：

SELECT t2.buildingName as 'Building Name', MAX(t1.roomPrice) AS 'Total Building Price'
FROM Table2 t2
INNER JOIN Table1 t1 ON t1.buildingNo = t2.buldingNo
GROUP BY t2.buildingName

Answer 3

试试这个

SELECT tab1.buildingNo, MAX(tab1.roomPrice)
FROM tab1 JOIN tab2 ON tab1.buildingNo = tab2.buildingNo
GROUP BY  tab1.buildingNo

如果您想要整个建筑物的总和，请使用此

SELECT tab1.buildingNo, SUM(tab1.roomPrice)
FROM tab1 JOIN tab2 ON tab1.buildingNo = tab2.buildingNo
GROUP BY  tab1.buildingNo

http://sqlfiddle.com/#!9/143c2/6

JOIN将一个表的每一行与另一表的所有行合并在一起。 如果将条件添加为“ ON ，则可以减少得到的组合。 在这种情况下，只有两个表上具有相同buildingNo行才会被“粘合”在一起。 然后，我们根据buildingNo它们进行分组，并仅使用具有roomPrice MAX的roomPrice或简单地创建SUM 。

Answer 4

尝试这个：

create table #Table2(buildingNo int, buldingName nvarchar(50), buildingCity    varchar(50))
  Insert into #Table2 values
  (1,'A','Delhi'),
  (2,'B','Delhi')


   Create Table #Table1  (roomNo int, buildingNo int, roomType  varchar(50), roomPrice int)
   Insert into #Table1 values
   (1,1,'2BHK',50000),
   (2,2,'2BHK',60000),
  (3,1,'1BHK',55000),
  (4,2,'2BHK',65000),
  (4,1,'2BHK',80000),
   (4,2,'2BHK',90000)

 SELECT max(roomPrice) AS [Total Building Price],buldingName FROM #Table1  t1
    JOIN  #Table2 t2
    ON t1.buildingNo=t2.buildingNo
    group by buldingName

Answer 5

如果只需要知道max（roomPrice），则不需要子查询：

SELECT tab2.buildingName, max(tab1.roomPrice) AS TotalBuildingPrice
FROM tab1
JOIN tab2 ON tab1.buildingNo = tab2.buildingNo
GROUP BY tab2.buildingName

但是，正如您的问题表明总建筑价格一样，您实际上可能指的是max（sum（））：

SELECT tab2.buildingName, sum(tab1.roomPrice) AS TotalBuildingPrice
FROM tab1
JOIN tab2 ON tab1.buildingNo = tab2.buildingNo
GROUP BY tab2.buildingName
ORDER BY TotalBuildingPrice DESC
LIMIT 1