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Presentation By:
Asad Raza (178)
Mohsin Javed (102)
Topics :
i. What is DBMS ? Data Items & Records.ii.Reasons for using DBMS?
What is DBMS?o A Data Base Management System is a collection of
logically related data files as well as programs required to manage that data.
o It is a computerized record-keeping system. It maintain data and provide it to user when required.
o Example: A bank DBMS may have separate files for the clients as follows:• Saving Accounts• Current Accounts & clients information etc.
Components Of DBMS :
1- Data:• Data is a collection of
facts/figures stored in the database.
2- Hardware: The physical components of a computer system.Example:• Secondary Storage & Main Memory.• I/O devices & Processors.
Components Of DBMS :
3- Software:• Software is a collection of programs used by
computer within a database system.• DBMS uses three types of software to enable
the database system work properly.i. OS Software: It manages all hardware components & software to run on computer.ii. DBMS Software: It manages the database in database system.
Components Of DBMS :iii.Application Programs: • These are used to access & process the data stored
in the database. 4- Personnel :- The people related to database system are called personnel. They are as follows: Database Administrators: They are responsible of the whole database system. They authorize access to database and monitor the use & working of database system. Application Programmers: They write application programs to access data from database.
Components Of DBMS : End Users: These peoples use application programs to perform different task on database. They include clerks , managers , directors etc. Hierarchy Of Data in DBMS: o Data in database is classified in a hierarchy.o A database contains
files>records>fields>characters. Field: • A combination of one or more characters.• Field data type: Indicates type of data in field.• Field Size: Defines maximum no of characters in a field.
Hierarchy Of Data in DBMS:
Record: • A collection of related
fields treated as single unit.
Example: Employee’s record. File: • A collection of related records
treated as single unit.• Files are stored on stored on
storage media like Hard Disk etc.
KEYS:
Primary Key: • An attribute or set of attributes that
uniquely identifies a row or record in a relation/table is known as primary key.
• A relation can have only one Primary Key.• Each value in Primary Key attribute must
be unique.• Primary Key cannot contain null values.
Candidate Key: • The attributes or set of attributes that
can be used as primary key is called Candidate Key.
Reg No Name Class
10 Asad C.A
20 Mohsin P.H.D
30 Zeeshan M.B.B.S
The attribute Reg No is Primary Key.
KEYS: Alternate Key: • The candidate keys
that are not selected as primary key are know as Alternate Keys.
Composite Key: • A primary key that
consists of two or more attributes is known as Composite Key.
KEYS:
Secondary Key: • An attribute or set of
attributes that is bases for retrieval is called S.K
• One Secondary Key value may refer to many records.
• Secondary Key can be a non-unique attribute.
Foreign Key: • A Foreign Key is an
attribute or set of attributes in a relation/table whose values match a primary key in another relation.
KEYS:
Sort/Control Key: • An attribute or set of attributes that is used to
physically sequence the stored data is called sort/control key.
Facilities Of DBMS: Adding new files to database. Inserting new data in existing files. Retrieving data from existing files. Updating data in existing files. Deleting data from existing files. Removing existing files from database.
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