Combining two tables is a very simple and easy SQL question that is being asked in many FAANG companies. 


There are two tables containing data related to one column.

SQL Schema for the first table named Person:


CREATE TABLE IF NOT EXISTS Person (personId int, firstName varchar(255), lastName varchar(255))

INSERT INTO Person (personId, lastName, firstName) values ('1', 'Wang', 'Allen')

INSERT INTO Person (personId, lastName, firstName) values ('2', 'Alice', 'Bob')



personId firstName lastName
1 Wang Allen
2 Alice Bob


SQL Schema for the second table named Address:


CREATE TABLE IF NOT EXISTS Address (addressId int, personId int, city varchar(255), state varchar(255))

INSERT INTO Address (addressId, personId, city, state) values ('1', '2', 'New York City', 'New York')

INSERT INTO Address (addressId, personId, city, state) values ('2', '3', 'California', 'California')
addressId personId city state
1 2 New York City New York
2 3 California California



Required Output:


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



We have checked both the tables and required output. It is very clear from the output that we should be using LEFT JOIN to get the desired output.


SELECT firstName, lastName, city, state FROM Person LEFT JOIN Address.personId=Person.personId;

This query will generate the required output.