27/12/2020
is the standard language for Relational Database System. All the Relational Database Management Systems (RDMS) like , , , , , and use SQL as their standard database language. Given the omnipresence of the database, it's expected from a programmer that he is familiar with essential database concepts like normalization and table design along with SQL. There are many databases, like , , , , etc. but knowing just one is enough. The critical point is that you should be familiar with the database. You should know how to insert/update/delete data and write SQL queries to retrieve it. Knowledge of advanced concepts like join an aggregate function is a big bonus, and if you want to get that, then the complete is a great place to start with.