Database Concepts: Points to remember

Computer Science : Database concepts and MySql : Database Concepts

Points to remember:

·        DBMS is a computer based record keeping system

·        Data is unprocessed data which contains any character, text, word or number has no meaning

·        Information is processed data, organized and formatted.

·        Examples of RDBMS are mysql, oracle, sql server, ibm db2

·        Redundancy means duplication of data in a database.

·        Data Consistency means that data values are the same at all instances of a database

·        Data Integrity is security from unauthorized users

·        Table is known a relation

·        A row is called a tuple

·        A column is known as an attribute

·        Types of data model are Hierarchical, Relational, Network, ER and Object model.

·        Hierarchical model is a simple tree like structure form with one-to-one relationship called parent-child relationship

·        Relational Model represents data as relations or tables

·        Network model is similar to Hierarchical model but it allows a record to have more than one parent

·        ER model consists of entities, attributes and relationships

·        Object model stores data as objects, attributes, methods, classes and inheritance

·        Normalization reduces data redundancy and improves data integrity

·        Different types of Relationship are one-to-one, one-to-many, many-to-one and many-to-many relationships

·        Database Normalization was proposed by Dr.Edgar F Codd

·        Relational Algebra is used for modeling data stored in relational databases and for defining queries on it.