Relational Database Management Systems

We've seen one of the factors that throw a great impact on the efficiency of data and types of database management schemes present in the development and manipulation of an efficient database. One thing must be clear for you by this time that a database is simply a powerful storage than a Hard Disk, made so because of the management we have for it. DBMS is the software version of such management/ governing scheme. There are Some goals that an efficient DBMS must aim at:

• Creation of a Database
• Efficient Handling of manipulations like add, modify or delete on the data
• Employ constraints for Database Security

Hence our DBMS must somehow satisfy these needs to have an efficient handling of data. One thing is that how much large the data may be, it must be stored such that the operations must be responded very quickly. For Example let us consider a reservation database, that handles the seats in a vehicle, a Bus say. If our database is so slow that each query takes considerable time in responding, passengers will sure have to struggle a lot. Because since the tickets are such a data which can't be shared, if a ticket is issued to two people, then we'll have a fight!!!

 Relational database solves such problems by employing table constructs on the data construction. The rows are all entirely data, and columns map to the owners or the identifier variables. The cell is an intersection of a row and a column. For example in the above figure, tutorial_id, title, company are the variables which hold the values below in the respective columns. In RDBMS, the table is a relation, a row and a column being the values of the relation. Here we need to know about two things about the entries in the table, they are 

• Entity
• Attribute

An Entity is the item being described in the table, and attribute being the values. Hence a table consists of Entities and attributes for the entities. A Relational Database is represented in the form of a relation between the attributes, the tables we generally speak about will be of the form

D(d1,d2,d3,.......dn) where d1, d2,... are all attributes which hold the column values.

Edgar F. Codd was the man behind the origin of a Relational Database Management Systems. He defined a relation as a one that satisfies 12 rules to be called so. We'll pause our discussion at this point and we'll discuss them in their full view next time...