Database Concepts

Database :- It is collection of information in such a way that computer program can quickly retrieve desired pieces of data and do operations.

DBMS ( Database management system) :- It is collection of programs that allows us to store, modify and extract information from database.

Data Independence :- Data independence implies that data stored at different levels should not affect each other when get changed.

Table :- A predefined row/column format for storing information in relational databasse.

Attributes :- Columns of table are called attributes.

Tuples :- Rows of table are called tuples.

Degree :- Number of attributes (columns) in a relation is called its degree.

Cardinality :- The number of tuples (rows) in relation is called cardinality.

Key :- Keys help in identifying, retrieving and establishing relationship among tables. There are various keys some of them are primary key, foreign key, alternate key, etc.

Data Integrity :- It means that one person can correctly and consistently navigate and manipulate the tables in database.

Entity Integrity :- It state that value of primary key can never be null and for each roe, it should be unique.

Referential Integrity :- It state that if a relational table has foreign key, then every value of foreign key must be either null or match the value in the relational table in which foreign key is a primary key.

Join :- It is used to combine related tuples from two relation. The join operator is cross product of two relations.

SQL (structured Query Language ) :- It is standard language used for communicating with RDBMS. It looks like English language.

DML ( Data Manipulation Language ) :- It is a part of SQL that provides statements for manipulating database. DML statements can modify the data stored in a database, but they can’t change its structured. Some of DML statements are : Insert Into, Delete , Select, Update, etc.

DDl ( Data Definition language ) :- It is a part of SQL that provides statements for creation and deletion of database. DDL statements are : Create Table, Alter Table, Drop Table, Create Index, etc.

Categories: News, Tech

Tagged as: