![Leetcode 175. Combine Two Tables Leetcode 175. Combine Two Tables](https://image.shishitao.com:8440/aHR0cHM6Ly9ia3FzaW1nLmlrYWZhbi5jb20vdXBsb2FkL2NoYXRncHQtcy5wbmc%2FIQ%3D%3D.png?!?w=700&webp=1)
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