Combine Two Tables
題意：
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
解題思路：
在這裡使用left join來幫助我們解這道題，left join表示以左邊的表格為主，加上用on 的keyword把符合條件的合起來。
SELECT Person.FirstName, Person.LastName, Address.City, Address.State
FROM Person LEFT JOIN Address ON Person.PersonId = Address.PersonId;