In 1971, IBM researchers created a simple non-procedural language called Structured English Query Language. or SEQUEL. This was based on Dr. Edgar F. (Ted) Codd's design of a relational model for data storage where he described a universal programming language for accessing databases.
In the late 80's ANSI and ISO (these are two organizations dealing with standards for a widevariety of things) came out with a standardized version called Structured Query Language or SQL. SQL is prounced as 'Sequel'. There have been several versions of SQL and the latest one is SQL-99. Though SQL-92 is the current universally adopted standard.
SQL is the language used to query all databases. It's simple to learn and appears to do very little but is the heart of a successful databaseapplication. Understanding SQL and using it efficiently is highly imperative in designing an efficient database application. The better your understanding of SQL the more versatile you'll be in getting information out of databases.
What's an RDBMS ?
This concept was first described around 1970 by Dr. Edgar F. Codd in an IBM research publication called "System R4 Relational".
A relationaldatabase uses the concept of linked two-dimensional tables which comprise of rows and columns. A user can draw relationships between multiple tables and present the output as a table again. A user of a relational database need not understand the representation of data in order to retrieve it. Relational programming is non-procedural.
[What's procedural and non-procedural ?
Programming languages areprocedural if they use programming elements such as conditional statements (if-then-else, do-while etc.). SQL has none of these types of statements.]
In 1979, Relational Software released the world's first relational database called Oracle V.2
What a DBMS ?
MySQL and mSQL are database management systems or DBMS. These software packages are used to manipulate a database. All DBMSs use their ownimplementation of SQL. It may be a subset or a superset of the instructions provided by SQL 92.
MySQL, due to it's simplicity uses a subset of SQL 92 (also known as SQL2).
What's Database Normalization ?
Normalization is the process where a database is designed in a way that removes redundancies, and increases the clarity in organizing data in a database.
In easy English, it means takesimilar stuff out of a collection of data and place them into tables. Keep doing this for each new table recursively and you'll have a Normalized database. From this resultant database you should be able to recreate the data into it's original state if there is a need to do so.
The important thing here is to know when to Normalize and when to be practical. That will come with experience. For now,read on...
Normalization of a database helps in modifying the design at later times and helps in being prepared if a change is required in the database design. Normalization raises the efficiency of the datatabase in terms of management, data storage and scalability.
Now Normalization of a Database is achieved by following a set of rules called 'forms' in creating the database.
These rules are 5in number (with one extra one stuck in-between 3&4) and they are:
1st Normal Form or 1NF:
Each Column Type is Unique.
2nd Normal Form or 2NF:
The entity under consideration should already be in the 1NF and all attributes within the entity should depend solely on the entity's unique identifier.
3rd Normal Form or 3NF:
The entity should already be in the 2NF and no column entry should bedependent on any other entry (value) other than the key for the table.
If such an entity exists, move it outside into a new table.
Now if these 3NF are achieved, the database is considered normalized. But there are three more 'extended' NF for the elitist.
BCNF (Boyce & Codd):
The database should be in 3NF and all tables can have only one primary key.
Tables cannot have...