Problem 175: Combine Two Tables
Categories: LeetCode-Database
175. Combine Two Tables
Table 1: Person
| Column Name | Type |
|---|---|
| PersonId | int |
| FirstName | varchar |
| LastName | varchar |
PersonIdis the primary key for this table.
Table 2: Address
| Column Name | Type |
|---|---|
| AddressId | int |
| PersonId | int |
| City | varchar |
| State | varchar |
AddressIdis the primary key for this table.
Write a SQL query that provides the following information for each person in the Person table, regardless of whether there is an address entry for that person:
FirstName, LastName, City, State
SQL script:
Create table Person (PersonId int, FirstName varchar(255), LastName varchar(255));
Create table Address (AddressId int, PersonId int, City varchar(255), State varchar(255));
Truncate table Person;
insert into Person (PersonId, LastName, FirstName) values ('1', 'Wang', 'Allen');
Truncate table Address;
insert into Address (AddressId, PersonId, City, State) values ('1', '2', 'New York City', 'New York');
Solution
Solution 1: LEFT JOIN
SELECT
FirstName,
LastName,
City,
State
FROM
Person
LEFT JOIN
Address ON (Person.PersonId = Address.PersonId);