Leet Code Day #175

175. Combine Two Tables

Write an SQL query 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.

My Answer:

SELECT Person.FirstName, Person.LastName, Address.City, Address.State

FROM Person

LEFT OUTER JOIN Address ON Person.PersonID = Address.PersonID

Explanation:

I started taking data classes for my degree and I am LOVING THEM. It is crazy to think that I may have finally found what I want to go into. Not to limit myself by any means but I am just excited that I am liking my classes this much. I decided to start up my leetcode practice to try and see how good at this stuff I can get. This is my 1st database Leetcode that I have ever done and I did pretty well with it.

Since we are combining two tables I knew that a join operation had to be done. So I wrote out the sequence for that. which includes "Select / FROM / JOIN ON"

Select - to select which attributes from which table to be presented

From the 1st table to join

JOIN the 2nd table to join

ON the key to match table 1 to table 2

The one question left to solve was which type of join to use. With the LEFT OUTER JOIN it would present the NULL values as stated in the problem description.

I am excited to continue on this journey.