Problem

Given a table of user data with the following schema:
CREATE TABLE users (
id INTEGER PRIMARY KEY,
username VARCHAR(255),
password VARCHAR(255),
salt VARCHAR(255)
);
Write a SQL query that returns the salt for a given user's password.
Example input:
id | username | password | salt
1 | alice | alicesecretpassword | alicesalt
2 | bob | bobsecretpassword | bobsalt
3 | charlie | charliesecretpassword | charliesalt
Example output:
salt
alicesalt
bobsalt
charliesalt

Solution

SELECT salt
FROM users
WHERE password = 'alicesecretpassword'
OR password = 'bobsecretpassword'
OR password = 'charliesecretpassword';

/*

This is the optimal solution because it is the most efficient way to get the salt for a given user's password.

*/