LeetCode 175. Combine Two Tables
题目
Table: Person
+-------------+---------+
| Column Name | Type |
+-------------+---------+
| PersonId | int |
| FirstName | varchar |
| LastName | varchar |
+-------------+---------+
PersonId is the primary key column for this table.
Table: Address
+-------------+---------+
| Column Name | Type |
+-------------+---------+
| AddressId | int |
| PersonId | int |
| City | varchar |
| State | varchar |
+-------------+---------+
AddressId is the primary key column for this table.
Write a SQL query for a report that provides the following information for each person in the Person table, regardless if there is an address for each of those people:
FirstName, LastName, City, State
题目大意 : 编写一个SQL查询，对于Person表中的每一个人，取出FirstName, LastName, City, State属性，无论其地址信息是否存在。
解题思路
- LEFT [OUT] JOIN
表Person与表Address作左外连接查询
SELECT Person.FirstName, Person.LastName, Address.City, Address.State
FROM Person LEFT JOIN Address ON Person.PersonId=Address.PersonId
