Question

房屋

id OwnerId    street
-----------------------
1  owner1     street1
2  owner2     street1
3  owner3     street2
4  owner4     street2
5  owner5     street3

正如您所看到的，在同一条街上可以有更多的所有者

我有另一张桌子，我希望从Houses表中插入所有者，但每条街只有一个

查询结果：

表StreetRepresentant

ownerId    street 
------------------
owner1     street1
owner3     street2
owner5     street3

（ownerId是表格的PK，如果重要的话。OwnerId在表Houses中是唯一的}

查询应该是：

INSERT INTO StreetRepresentant (ownerId , street ) 
SELECT ownerId , street 
FROM Houses
--what should be here to get only 1 owner for each street? ...

Answer 1

您可以按街道分组，然后使用MIN()功能返回每条街道的最低值（根据您的示例）ownerId。

SELECT MIN(ownerId) , street 
FROM Houses
GROUP BY street

Answer 2

INSERT INTO StreetRepresentant (ownerId , street ) 
SELECT ownerId , street 
FROM Houses h
GROUP BY h.street, h.ownerId

Answer 3

看看像

这样的东西

SELECT  Street,
        MIN(ID) FirstAvailableID
FROM    Houses
GROUP BY    Street

Answer 4

在选择行时使用Distinct关键字，希望它能够正常工作。

SQL首先选择具有给定名称的SQL

4 个答案: