Data: are the raw facts and figures which can be recorded.
for eg, name of the student, course details, fees details
etc.
ABEL, JAVA,
10000
Information: are the processed data or organized data which
gives complete meaning.
for eg, Abel learning Java course and paid 10000 towards
fees.
Database: is a logical collection of relevant data.
for eg, university database, railway database etc.
DATABASE MANAGEMENT SYSTEM(DBMS): It is collection of
programs or software
which manages the database.
Data is stored in files (.dbf)
Benefits of the Database Approach
• Redundancy can be reduced
• Inconsistency can be avoided
• Data can be shared
• Standards can be enforced
• Security restrictions can be applied
• Integrity can be maintained
Keys:
KEY : IS A ATTRIBUTE WITH WHICH WE CAN UNIQUELY IDENTIFY
EACH ROW IN THE TABLE.
Natural Key: A natural key is one or more existing data
attributes that are unique
to the business concept. For the Customer table there was
two candidate keys, in
this case CustomerNumber and SocialSecurityNumber.
Surrogate key: Introduce a new column, called a surrogate
key, which is a key that
has no business meaning.
primary key= It is attribute/attributes which will not allow
to store the null
value and duplicate value, it is also useful to identify
each row uniquely in
the table. NOT NULL + UNIQUE (The minimal candidate key is
known as primary key).
candidate key = are the attributes(COLUMNS) which can
qualify for the primary key.
alternate key -> the remaining candidate key which can
qualify for the primary key,
but it is not primary key.
foreign key -> It is the attribute/attributes whose
characteristic is dependent on
the characteristic of another atrribute/primary key
attribute. foreign key column
can have only those value which is there in the primary key
column and it can have
null values, it can have duplicate values also.
relational database: collection of related/relevant data
stored in tables(collection
of relations(tables) or two-dimensional tables).
RDBMS - Relational DataBase Management System
is a software or collection of programs which manages the
relational database.
Dr. E.F.Codd proposed the relational model for database
systems.
It is the basis for RDBMS,
RDBMS consists of
Collection of objects or relations(tables),
set of operators to act on the relations, and
data integrity for accuracy and consistency
DBMS:
NDBMS->Network Database Management system
HDBMS->Hierarchical Dabatabase Management system
RDBMS->Relational Database Management system
ORDBMS=rdbms+odbms ->Object Relational Database
Management system.
TABLE:IT IS A COLLECTION OF ROWS AND COLUMNS.
row, column (key column, non-key column), foreign key
column,
cell/field (intersection of a column and a row),
null(unavailable, unassigned, unknown, inapplicable),
null is not same as a zero or a blank space
Columns of any datatype can contain nulls.
metadata - data about data.
data dictionary(SYSTEM TABLE)
Database schema: Collection of Objects
Database user: Account in database
In oracle schema and user share same name
One user is associated with one schema only.
SQL - STRUCTURE QUERY LANGUAGE
SEQUEL - STRUCTURE ENGLISH QUERY LANGUAGE
ANSI & ISO HAS APPROVED THIS SQL LANGUAGE AS A STANDARD
LANGUAGE FOR ALL THE
RDBMS SOFTWARES.
ANSI - AMERICAN NATIONAL STANDARD INSTITUTE.
ISO - INTERNATIONAL STANDARD ORGANIZATION.
SQL: Structured Query Language
==============================
Can be pronounced as SEQUEL(Structure English Query
Language)
Sub Languages in SQL
1) Data Definition Language (DDL)
2) Data Manipulation Language (DML)
3) Transaction Control Language (TCL)
4) Data Control Language (DCL)
DDL (DATA DEFINITION LANGUAGE):
CREATE, ALTER, DROP, TRUNCATE, RENAME, COMMENT
DML (DATA MANIPULATION LANGUAGE):
INSERT, UPDATE, DELETE, SELECT, MERGE
TCL (TRANSACTION CONTROL LANGUAGE):
COMMIT, ROLLBACK, SAVEPOINT
DCL (DATA CONTROL LANGUAGE):
GRANT, REVOKE
SQL Command Line (SQL*Plus)
iSQLPlus (discontinued after Oracle 10g)
SQL Developer (introduced with Oracle 11g)
TOAD - GUI(THIRD PARTY TOOL)
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