[LeetCode 175] Combine Two Tables

문제 바로가기

Description

---

Table: Person

+-------------+---------+
| Column Name | Type    |
+-------------+---------+
| personId    | int     |
| lastName    | varchar |
| firstName   | varchar |
+-------------+---------+

personId is the primary key (column with unique values) for this table. This table contains information about the ID of some persons and their first and last names.

Table: Address

+-------------+---------+
| Column Name | Type    |
+-------------+---------+
| addressId   | int     |
| personId    | int     |
| city        | varchar |
| state       | varchar |
+-------------+---------+

addressId is the primary key (column with unique values) for this table. Each row of this table contains information about the city and state of one person with ID = PersonId.

Write a solution to report the first name, last name, city, and state of each person in the Person table. If the address of a personId is not present in the Address table, report null instead.

Return the result table in any order.

The result format is in the following example.

Example 1

---

• Input:
  • Person table:

    +----------+----------+-----------+
    | personId | lastName | firstName |
    +----------+----------+-----------+
    | 1        | Wang     | Allen     |
    | 2        | Alice    | Bob       |
    +----------+----------+-----------+
    

  • Address table:

    +-----------+----------+---------------+------------+
    | addressId | personId | city          | state      |
    +-----------+----------+---------------+------------+
    | 1         | 2        | New York City | New York   |
    | 2         | 3        | Leetcode      | California |
    +-----------+----------+---------------+------------+
    

• Output:

  +-----------+----------+---------------+----------+
  | firstName | lastName | city          | state    |
  +-----------+----------+---------------+----------+
  | Allen     | Wang     | Null          | Null     |
  | Bob       | Alice    | New York City | New York |
  +-----------+----------+---------------+----------+
  

• Explanation:
  • There is no address in the address table for the personId = 1 so we return null in their city and state.
  • addressId = 1 contains information about the address of personId = 2.

Constraints

---

Code

---

내 제출

---

# Write your MySQL query statement below

SELECT p.firstName, p.lastName, a.city, a.state
FROM Person p LEFT OUTER
JOIN Address a ON p.personId = a.personId;

Runtime	Memory
369 ms	0.0 B

다른 풀이

---

# Write your MySQL query statement below
select p.firstName,
p.lastName, 
COALESCE(a.city, NULL) AS city,
COALESCE(a.state, NULL) AS state
from Person p left join Address a on p.personId = a.personId

Reference

---