Introduction to Relational Database Management System
Introduction to Relational Database Management SystemPrepared
by: Romer Ian O. PasocA relational DBMS is a special software that
is used to manage the organization, storage, access, security and
integrity of data.This specialized software allows the application
developer or user to focus on the user interface, data validation
and screen navigationThe application system can then simply makes a
call to the RDBMS when inserting, modifying, deleting or displaying
data.What is an RDBMS?RBMS is the most common type of database
management system.Other types includes hierarchical and network
databases.A relational DBMS stores information in a set of tables,
each of which has a unique identifier or primary key.The tables are
then related to one another using foreign keys.A foreign key is
simply the primary key of another table.Almost all major industries
or companies, and even medium size establishments utilizes DBMS and
there is a big chance that most of these are RDBMSs.Real Life
ApplicationsThe relational model is a collection of relations
required to build a database. Tables in an RDBMS are technically
called Relations.
In the relational model, each row in the relation consists of
set of related data values.
Each row shares some reality which corresponds to the real world
entity or relationship
Rows in a relation is technically called TuplesThe Relational
ModelEvery relation is given a unique name. A relation comprises of
columns. These columns represents the set of related values
(domain) that pertains to its attribute. Example, A relation:
person, can have an attributes: name, age, address . These
attributes should only contain information that belongs to its
intended data to be stored (domain).
Proper naming of relations and its columns is essential for
identification of data to be extracted.
Technically, a column in our relation is called an
AttributeStudent_ID
(STRING)S_Name(STRING)Age(INT)B_day(DATE)1023-PRPJuan1909/09/19891231-IGPPedro2011/22/19882312-ICTMaria1702/21/19912131-HGQCrispin1605/09/19921923-YYTBasilio2112/25/1987BASIC
PARTS OF A RELATIONStudent Name of the relationStudent_ID, S_Name,
Age, and B_day AttributesString, Int, and Date DomainAll 5 rows
TuplesSTUDENTRELATION NAMETable nameATTRIBUTESColumnsDOMAINData
TypesTUPLESRows/RecordsBASIC PARTS OF A RELATIONWe can actually
write the structure of a relation in this format:
relation_name (attribute1:domain,
attribute2:domain,attributeN:domain)
Why the underline on the first attribute?Represents
keysNotationCOMMON DATA TYPES (MS ACCESS)Text/StringUse for text or
combinations of text, numbers, and some symbols. 255 characters
maximumMemoMemo is used for larger amounts of text. Stores up to
65,536 characters.Integer/IntAllows whole numbers between -32,768
and 32,767LongAllows whole numbers between -2,147,483,648 and
2,147,483,647COMMON DATA TYPES (MS ACCESS)SingleSingle precision
floating-point. Will handle most decimalsDoubleDouble precision
floating-point. Will handle most decimalsCurrencyUse for currency.
Holds up to 15 digits of whole dollars, plus 4 decimal
places.Tip:You can choose which country's currency to useCOMMON
DATA TYPES (MS ACCESS)AutoNumberAutoNumber fields automatically
give each record its own number, usually starting at 1Date/TimeUse
for dates and timesYes/NoA logical field can be displayed as
Yes/No, True/False, or On/Off.
What is a Schema?What is an Instance and how does it differ to
Schema?What are the different types of keys in an RDBMS?What are
the 4 different types of relationships?
Assignment
