COM 111 LECTURE SCHEDULE 15

COM 111 LECTURE SCHEDULE 15

Normalization Techniques, Types of Databases, Introduction to Structured Query Language

NORMALIZATION:

            The process of reducing data redundancy in a relational database is called normalization. This saves the storage space and reduces the time queries taken to execute. The fundamental principle of normalization is: the same data should not be stored in multiple places. No information is lost in the process. The advantages are:

• It frees the database
• It reduces the need to restructure the database as new data are introduced
• It allows for simple data access.

There are different normal forms like first normal form (1NF), second normal form (2NF), third normal form (3NF), etc.

TYPES OF DATABASES

There are 2 different types:

i.                    Centralized database: Here, application processing is shared between numerous clients. Eg: DB2, Oracle server

ii.                  Distributed database: Here, the database is physically located at various locations.   Eg: multinational corporate company database.

INTRODUCTION TO STRUCTURED QUERY LANGUAGE (SQL)

SQL stands for Structured Query Language and  SQL is an ANSI (American National Standards Institute) standard.

What Can SQL do?

•           SQL can execute queries against a database

•           SQL can retrieve data from a database

•           SQL can insert records in a database

•           SQL can update records in a database

•           SQL can delete records from a database

•           SQL can create new databases

•           SQL can create new tables in a database