Question: https://codility.com/demo/take-sample-test/sql_sum/ Question Name: Sql-Sum or SqlSum This question is too easy to be a serious training lesson. Most likely, it’s a live test for SQL challenges on Codility.com. The following solution works in both PostgreSQL and SQLite.
SELECT SUM(v) FROM elements
Question: https://oj.leetcode.com/problems/combine-two-tables/ Question Name: Combine Two Tables This problem is used to check our knowledge in JOIN. LEFT JOIN is used here. But we should also know about the others like INNER JOIN, RIGHT JOIN and OUTER JOIN.
# Write your MySQL query statement below
SELECT FirstName, LastName, City, State
FROM Person LEFT JOIN Address
ON Person.PersonId = Address.PersonId