Computer

Write a short note on Relational Calculus.

An operational methodology, founded on predicate calculus, dealing with descripitive expressions that are equivalent to the operations of relational algebra. Codd’s reduction algorithm can convert from relational calculus to relational algebra. Two forms of the relational calculus exist: the tuple calculus and the domain calculus. Codd proposed the concept of a relational calculus (applied predicate…

What is a functional dependency in a relation?

A functional dependency is a property of the semantics of the attributes in a relation. The semantics indicate how attributes relate to one another and specify the functional dependencies between attributes. When a functional dependency is present, the dependency is specified as a constraint between the attributes. Consider a relation with attributes A and B,…

What is Normalization in DBMS?

Normalization is a formal process for determining which fields belong in which tables in a relational database. Normalization follows a set of rules worked out at the time relational databases were born. A normalized relational database provides several benefits: Elimination of redundant data storage. Close modeling of real world entities, processes, and their relationships. Structuring…

What is the difference between Delete and Truncate Statement of SQL?

The DELETE Statement deletes only the rows from the table based on the condition given in the where clause or deletes all the rows from the table if no condition is specified, but does not free the space containing the table, whereas the TRUNCATE statement deletes all the rows of the table and frees up…

What is a DBMS?

Database Management System is a collection of computer programs that allow storage, modification, and extraction of information from a database. There are many different types of DBMSs, ranging from small systems that run on personal computers to huge systems that run on mainframes. The following are examples of database applications: computerized library systems, automated teller…