Database Leetcode 175 Combine Two Tables

Database Leetcode 175 Combine Two Tables

目录:

1. 题目

2. 解题思路

3. 他山之石

1. 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

2. 解题思路

该题使用外连接的知识点:

select p.FirstName, p.LastName, a.City, a.State from Person p left outer join Address a on p.PersonId = a.PersonId;

3. 他山之石

来自讨论区的ohini

SELECT FirstName, LastName, City, State FROM Person LEFT JOIN Address USING(PersonId);