Leetcode 175. Combine Two Tables

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

本题的思路很简单，由于FirstName, LastName, City, State 来自两个不同的 table， 所以要用join。由于要求必须显示人名，即使没有地址相关信息，说明要用LEFT JOIN。经测试LEFT JOIN和LEFT OUTER JOIN效果一样。

 # Write your MySQL query statement below
 SELECT FirstName, LastName, City, State FROM Person
 LEFT JOIN Address ON Person.PersonId = Address.PersonId