Database Management Systems

A database management system (DBMS) is a program that knows how to open database files and manage the contents of the tables. A DBMS can manage multiple databases.

There a many, many different DBMSs out on the market today, but fortunately, they can be grouped together in broad categories or types.

Relational

Relational Database Management Systems (RDBMS) are the most popular type of database management systems today. Some types of RDBMSs include: MySQL, Oracle, SQL Server, and SQLite. This type of system requires predefined schemas and enforces strict rules to follow the table structure. This focus on structure is what makes RDBMSs reliable with high levels of data integrity. A database of Relational Database Management Systems is made up of tables. These tables have a predefined structure and share a formal relationship with one another.

All RDBMSs use a version of the Structured Query Language (SQL).

NoSQL

While Relational Database Management Systems are the most popular system today, a group of type of database systems, commonly known as NoSQL database systems, are gaining in popularity, especially with the rise of Social Media. Some types of NoSQL database management systems include: MongoDB, CouchDB, and Redis.

Data doesn't always fit neatly in a predefined mold. With NoSQL data can be stored in many different ways: it can be column-oriented, document-oriented, graph-based or organized as a KeyValue store. This allows for data to be organized without a structured schema.