What is Database?
A database is a separate application that stores a collection of data. Each
database has one or more distinct APIs for creating, accessing, managing,
searching, and replicating the data it holds.
Other kinds of data stores can be used, such as files on the file system or
large hash tables in memory but data fetching and writing would not be so fast
and easy with those type of systems.
So now a days we use relational database management systems (RDBMS) to store
and manager huge volume of data. This is called relational database because all
the data is stored into different tables and relations are established using
primary keys or other keys known as foreign keys.
A Relational DataBase Management System (RDBMS) is a software that:
- Enables you to implement a database with tables, columns, and indexes.
- Guarantees the Referential Integrity between rows of various tables.
- Updates the indexes automatically.
- Interprets an SQL query and combines information from various tables.
Before we proceed to explain MySQL database system, lets revise few
definitions related to database.
- Database: A database is a collection of tables, with related
- Table: A table is a matrix with data. A table in a database looks
like a simple spreadsheet.
- Column: One column (data element) contains data of one and the
same kind, for example the column postcode.
- Row: A row (= tuple, entry or record) is a group of related data,
for example the data of one subscription.
- Redundancy: Storing data twice, redundantly to make the system
- Primary Key: A primary key is unique. A key value can not occur
twice in one table. With a key you can find at most one row.
- Foreign Key: A foreign key is the linking pin between two tables.
- Compound Key: A compound key (composite key) is a key that
consists of multiple columns, because one column is not sufficiently unique.
- Index: An index in a database resembles an index at the back of a
- Referential Integrity: Referential Integrity makes sure that a
foreign key value always points to an existing row.
MySQL is a fast, easy-to-use RDBMS used being used for many small and big
businesses. MySQL is developed, marketed, and supported by MySQL AB, which is a
Swedish company. MySQL is becoming so popular because of many good reasons.
- MySQL is released under an open-source license. So you have nothing to
pay to use it.
- MySQL is a very powerful program in its own right. It handles a large
subset of the functionality of the most expensive and powerful database
- MySQL uses a standard form of the well-known SQL data language.
- MySQL works on many operating systems and with many languages including
PHP, PERL, C, C++, JAVA etc.
- MySQL works very quickly and works well even with large data sets.
- MySQL is very friendly to PHP, the most appriciated language for web
- MySQL supports large databases, up to 50 million rows or more in a
table. The default file size limit for a table is 4GB, but you can increase
this (if your operating system can handle it) to a theoretical limit of 8
million terabytes (TB).
- MySQL is customizable. The open source GPL license allows programmers to
modify the MySQL software to fit their own specific environments.
Before You Begin:
Before you begin this tutorial you should have a basic knowledge of the
information covered in our PHP and HTML tutorials.