Joins are for lazy people?

I recently had a discussion with another developer who claimed to me that JOINs (SQL) are useless. This is technically true but he added that using joins is less efficient than making several requests and link tables in the code (C# or Java).

What"s the difference between (INNER JOIN,LEFT JOIN,RIGHT JOIN,FULL JOIN) in Mysql

I want to know What's the difference between INNER JOIN,LEFT JOIN,RIGHT JOIN,FULL JOIN in Mysql

Best way to join tables using sqlite in android

I am trying to find out the best way to do a simple table join on my two tables using a sqlite database in an android application. Is the simplest way to use CursorJoiner or is there any easier way?