[LeetCode] 175. Combine Two Tables

1. 문제

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. 답

SELECT FirstName, LastName, City, State
FROM person
    LEFT JOIN address ON person.personid = address.personid

---

3. KEY POINT

 

• LEFT JOIN : 모든 사람의 주소 정보가 없을 수 있으므로 INNER JOIN이 아닌 LEFT JOIN을 사용

---

 

leetcode.com/problems/combine-two-tables/

Combine Two Tables - LeetCode