At the most basic form, the database schema is the representation of the logical configuration of the relational database, as a whole or as a part. It can also be defined as the skeletal structure which demonstrates the entire database through a logical view. It may exist only as a visual representation or as a group of formulae which govern a database. These formulae are communicated through a data definition language for the system to understand, such as SQL.
We all use many URLs on a daily basis. Sometimes we type them, sometimes we are just redirected to one URL by another. It is interesting to know that most of us think http://google.com or http://facebook.com are just URLs, but only a few know that we can also refer to them as the URI with the “I”. The URI, in fact, is a superset of URL and something called as a URN. We can thus safely conclude that all URLs are URIs. The opposite is not true, though.
MySQL is one of the most popular relational database management systems. It is developed and maintained by the Oracle Corporation. Other than Drupal, Joomla, and WordPress, MySQL is used by global brands like Facebook, Flickr, Twitter, and YouTube.
A data structure can be any organization, management, and storage format of data that allows efficient access and modification. It is a collection of data values, relationships amongst them, and the various functions or operations that can be applied to the data.