What Is Relational Databases
What Is Relational Databases
Definitions :
- A database is a collection of data.
- A database system is a system for
storing collections of data in some
organized way.
- It uses a structure that
allows us to identify and access data in
relation to another piece of data in the database.
- Often, data in a relational database is organized into tables.
What is a Relational Database Management System (RDBMS)?
- A relational database
management system (RDBMS) is a program that allows you to create, update, and
administer a relational database.
- Most relational database
management systems use the SQL language to access the database.
What is SQL?
- SQL (Structured Query Language) is a programming language used to communicate with data stored in a relational database management system.
Manipulating Data
Querying Data
Structuring Data
Joins & Groupings
The powerful
properties of the database :
- Persistence (allowing
access later, after it was created).
- Shared source of
truth accessible by many users.
- Ability to store many types of data (efficiently).
- Concurrency control
(handling multiple DB actions at once ).
- All data is stored in
tables.
- Every table is
characterized by a list of columns with data types per column, and it's set of
data (organized in rows)
- Comes with rules for
enforcing data integrity, such as constraints and triggers.
Popular
relational database vendors for the web :
1- MySQL
MySQL is the most popular open
source SQL database.
It is typically used for web
application development, and often accessed using PHP.
The main advantages of MySQL are
that it is easy to use, inexpensive, reliable (has been around since 1995), and
has a large community of developers who can help answer questions.
Some of the disadvantages are that
it has been known to suffer from poor performance when scaling, open-source
development has lagged since Oracle has taken control of MySQL, and it does not
include some advanced features that developers may be used to.
2- PostgreSQL
PostgreSQL is an open-source SQL
database that is not controlled by any corporation.
It is typically used for web
application development.
PostgreSQL shares many of the same advantages as MySQL.
It is easy to use, inexpensive, reliable and has a large
community of developers.
It also provides some additional
features such as foreign key support without requiring complex configuration.
The main disadvantage of PostgreSQL
is that it can be slower in performance than other databases such as MySQL.
It is also slightly less popular
than MySQL.
3- OracleDB
Oracle Corporation owns Oracle
Database and the code are not open-sourced.
Oracle DB is for large
applications, particularly in the banking industry.
Most of the world’s top banks run
Oracle applications because Oracle offers a powerful combination of technology
and comprehensive, pre-integrated business applications, including essential
functionality built specifically for banks.
The main disadvantage of using
Oracle is that it is not free to use like its open-source competitors and can
be quite expensive.
4- SQLServer
Microsoft owns SQL Server.
Like
Oracle DB, the code is close sourced.
Large enterprise applications
mostly use SQL Server.
Microsoft offers a free entry-level version called Express but
can become very expensive as you scale your application.
5- SQLite
SQLite is a popular open-source SQL database.
It can store an entire database in a single file.
One of the most
significant advantages this provides is that all of the data can be stored
locally without having to connect your database to a server.
SQLite is a popular choice for
databases in cellphones, PDAs, MP3 players, set-top boxes, and other electronic
gadgets.
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