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.