Types of Databases - Relational
Relational databases, on the other hand, organize data as logically independent tables. This is a more natural way to organize information, but there is a catch .. in order to tie all of the tables into one database, you have to tell the software how each piece of data is related to every other piece of data.
Sometimes this process is easy, and more often than not relationships between data can be expressed mathematically. Sometimes, however, this process is very complicated.
What may appear as a very simple relationship to us, may require a long and complicated algebraic equation to be understood by the computer.
Making relational databases to work requires the skills of a database programmer ... someone with a strong understanding of relational algebra.