[LeetCode] 175. Combine Two Tables

Problem

About:
LEFT JOIN, LEFT JOIN USING and NATURAL LEFT JOIN

Solution:
1.

SELECT FirstName, LastName, City, State
FROM Person
LEFT JOIN Address
ON Person.PersonId = Address.PersonId;

1. 2.

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

1. 3.

SELECT FirstName, LastName, City, State
FROM Person
NATURAL LEFT JOIN Address;

Note:
left join regardless whether there is an address for each of those people.
So we cannot use “WHERE” here(“WHERE” is used for inner join).