Dr. E. F. Codd worked to improve the working of DBMSs for handling large volumes of data. He applied the rules of mathematics for solving the problems of earlier database models. Some important problems were:
• Data integrity
• Data redundancy
Dr. Codd presented a paper “A Relational Model of Data for Large Shared Databanks” in June I 970 that contained 12 rules. A DBMS that satisfies these rules is called a full Relational Database Management System (RDBMS). The term “Relation” is also derived from the “Set theory” of mathematics.
In a relational model, data is stored in relations. Relation is another term used for table. A table in a database has a unique name that identifies its contents. Each table can he called an intersection of rows and columns. An important property of table is that the rows are unordered. A row cannot be identified by its position in the table. Every table must have a column that uniquely identifies each row in the table.
Advantages of a Relational Database Model:
Some important advantages of a relational database model are as follows:
1. Data Integrity:
It allows data integrity from field level to table level to avoid duplication of records. It detects records with missing primary key values at the relationship level to ensure valid relationships between tables.
2. Data Independence:
The implementation of database will not be affected by changes made in the logical design of the database or changes made in the database software.
3. Data Consistency &. Accuracy:
Since multiple level check and constraints are built-in, data is accurate and consistent.
4. Easy Data Retrieval & Sharing:
Data can be easily extracted from one or more than one tables. Data can also be easily shared among users.
comment closed