Structured Query Language (SQL) is a standardized programming language that is used to manage relational databases and perform various operations on the data in them.
SQL Cheat Sheet
MongoDB is a document-oriented NoSQL database used for high volume data storage. Instead of using tables and rows as in the traditional relational databases, MongoDB makes use of collections and documents. Documents consist of key-value pairs which are the basic unit of data in MongoDB. Collections contain sets of documents and function which is the equivalent of relational database tables.