SQL History and Why we are using relational Databases.

SQL is an non-procedural language which is used to operate the relational database. This includes the creation, deletion and modification of objects.

In 1970's E.F.CODD introduced DSL/ALPHA language which was used to operate the relational databases. And in this data model, We are storing the data in 2-Dimensional format(Rows and columns).

Later IBM systems developed simplified version of DSL/ALPHA language called SQUARE. Again IBM modified the this square language into sequel.

And finally it modified as SQL(Present we are using).

SQL: Structured query language.

Why We are using relational data base?

In Olden days we were using Books and Flat files to store the data. This is not the secure way to store the data. Below are the drawbacks So that now a days we are using relational databases.

Drawbacks:

1. Data Redundancy:  Data redundancy is nothing but duplicate data. Suppose you are using hard disks to store the data. So in this case, We can copy the existing file and store the same file in other directory/location. So this duplicate data.

2.Data In-Consistency : The same way, If we change the data in one location this won't be effect in other location of hard drive. This is called as "data in-consistency".

3. Data Intensity : Data intensity means, to maintain proper data(valid data). If you want to maintain the proper data in flat files, We have to use/develop application programs in high level language.

But in relational database, we have the constraints to maintain proper data. I will explain in detailed about the constraints in my coming classes.

4.Data Security :  Data stored in flat files can't be secured where as in database we have "roll based security".

5.Data Indexing : If we want to fetch the data very fast from database then will use the indexing mechanism where as flat files doesn't support the indexing. So we can't fetch the data very fast.

So to overcome all the above issues, IBM introduced the a new software called DBMS software and which is used to store/maintain the data efficiently.

DBMS: Database management system.

DBMS Definition:  DBMS means, It is a collection of programs written to manage the database.

                                Collection of programs called as Software.

                                Examples: Oracle, Sql server, MySQL, DB2,Teradata...….etc.

If we install the DBMS software into our system then automatically system will allocate some memory in hard disk . This is called as physical data base. And also an user interface will create to interact with database directly or through an interface.