SQL stands for Structured Query Language, and identifies what has been for many years the standard within the field of data storage. The base for this programming language, employed for storing and querying data, are the so-called relational data bases. The theory behind these data bases was first introduced by IBM engineer Edgar F. Codd, and is based on the following main elements:

• Tables, each of which represent an entity
• Columns, each of which represent an attribute of the entity
• Rows, each one representing a record of the entity
• Key attributes, which permit us to relate two or more tables together, establishing relations between them

Starting from these main elements, SQL language provides a concise and effective way to query and retrieve this data. Moreover, basilar data munging operations, such as table merging and filtering, are possible through SQL language. 

As previously mentioned, SQL and relational databases have formed the vast majority of data warehouse systems around the world for many, many years. A really famous example of SQL-based data storing products is the well-known Microsoft Access software. In this software, behind the familiar user interface, hide SQL codes to store, update, and retrieve user's data.