Information Management unit 3 Database management systems

INFORMATION
MANAGEMENT
UNIT 3: DATA BASE
MANAGEMENT SYSTEM
PREPARED AND PRESENTED BY,
GANESHA PANDIAN N
1

Content 2
1. DBMS (Database Management System)
2. HDMBS (Hierarchy based Data base management
system)
3. NDBMS (Network Database management system)
4. RDBMS (Relational Database Management System)
5. Query processing
6. SQL
7. Concurrency Management
8. Data Warehousing and data mart

File concepts 3
 A data element or field – logical collection of
characters
 A record – collection of logically grouped data
elements
 A record – usually a collection of data
elements describes entity
 A file is a collection of records of one type
(e.g.) details of employee record –”Employee
file”

File structure
 The way you choose to store records on
magnetic media called “File structure”
1. Sequential file structure – one way to store
the employee records sequentially using an
ID. The retrieval of data is difficult. The
most inexpensive and economical one
4
Contd…

2. Direct file structure
 Another way to store records is to store
randomly – allows direct access to data
in storage devices. Easy and direct
retrieval. But sometimes multiple
storage slows down the system
5
Contd…

3. Indexed sequential file
structure
 Third way to store records is sequentially on a direct
access medium
 Index is maintained as records are added to the file
 This method is called “Indexed sequential access
method” ISAM
 But indexed files require maintenance of the indexes.
 The system lead to slow performance where direct
access saves time
6

Accessing records
 Organization or manager need to:
1. Adding new record to a file
2. Deleting records from a file
3. Modifying records in a file
4. Viewing records in a file
5. Creating reports from records in a file
7

Inverted files
 ID method uses primary key for finding
and identifying stored data.
 Secondary key used that have
secondary indexes called “Inverted
Keys”.
8

Linked files
 The set of data retrieved by the pointer
when the search of records called
“Linked lists”.
 The method use to store records, affect
the access/retrieval of data
9

File structures
 File structure not only affect the access to data or record
but also processing of data or record.
1. File structures in online/real-time processing:
Here process is online/real time, so the direct
access of records either indexed sequential or direct
structure used.
2. File structures in batch processing:
Sequential access file structure – help in accessing
of records in the accumulated batch of files and the
entire batch is processed
Appropriate file structure should be used for the type of
processing requirement
10

Data base concepts
 Database – collection of related files; files is a
collection of records
Data independence – the lack of data independence –
any tie the record format of a file was changed.
This change will affect all corresponding files
Data redundancy – single record type file systems
Data consistency – update of data in file may not
ensure update in associated files/records. Data
inconsistency
11

Database Management Systems
(DBMS)
 DBMS – collection of software programs that
1. Store data in a uniform and consistent way
2. Organizes data into records in a uniform and
consistent way
3. Allows access to the data in a uniform and
consistent way
DBMS retrieves data from databases and provides
them to the application programs
12

Diagrammatic representation of
Process of DBMS
13
(DBMS) Database
Management System Database
Application
program
Application
program

Components of DBMS
- Organization mostly purchase Database
Management system software from vendors
1. Data dictionary/directory:
Contains the names and description of every data
element in the database
(e.g.) Data element name: “STOCKNUM”
description: No. of inventory item
14
Contd…

2. Data Language: Programmers use a
special language uniformly called “Data
Description Language” (DDL) – describe
the characteristics of the data element
(e.g.) command language –
“FIND,GET&INSERT
15
Contd…

3. Teleprocessing monitors:
It is a communication software package that
manages communication between the
database and remote terminals.
(e.g.) customer orders processed in branch or
store and sent to the database located in
Headquarters
16
Contd…

4. Application development tools:
It is a program designated to help
programmers develop application
programs that use the database
(e.g.) CASE tools (Computer Aided
Software Engineering)
17
Contd…

5. Security software:
A security software provides the
variety of tools to shield the
database from unauthorized access
and from unwanted viruses
18
Contd…

6. Archiving, Backup and recovering system:
Archiving programs – database manager with tools to
make copies of the database – in case original records in
database – damaged or destroyed.
Restart/recovery systems – tools used to restart the
database and to recover lost data in event of a failure
Back up systems – making copies of data and store safer
19
Contd…

7. Report writers:
-report writers – design of
output requirement needed by
the end user
20
Contd…

8. Query Language:
It is a set of commands – primarily for accessing data from a
database
three tools – SQL (structured Query Language); NLQ(Natural
Language Queries) and QBE (Query by Example)
(e.g.) SQL queries SELECT NAME,ADDRESS,CITY
FROM CUSTOMER
WHERE COUNTRY=“IN”
NLQ Queries “LIST THE NAMES AND ADDRESS OF ALL
CUSTOMERS IN INDIA”
QBE queries – does not require statement – any text or picture
21
Contd…

9. Multiple platform databases:
Some vendors provide DBMS
software work on many different
hardware and OS platforms.
22
Contd…

10. Web server software:
Vendors provide integrated WWW
server software with DBMS
The software turns the computer system
having the database into a web server
and enables users with web connectivity
23

The database administrator
- Development of DBMS has created a need for
organizational changes within firms
- Focal point of changes – lead to position of the database
administrator
- The company’s functional database shared by other
department – no need of DBA
- Data base Administrator maintains data consistency and
security
24

View of data
 Any data base contains two types of data
1. Actual data – such as employee names and so on…
2. Meta Data – how each data element relates to other
data element
Data in the database have 2 views
1. Logical View – Way user perceive records in the
database
2. Physical view – records are actually organized and
stores on the storage media
25
Contd…

The schema – is a description of the logical
view of a database
Common tool used to design schema in an
entity relationship diagram
Sub-system – A Less comprehensive logical
view of the database
- View used by an application programmer,
an application program or a user.
26

Database models
 Data in one record must have relationship with data in
another record
 Finding the relationship in large organization is
complex and so some of models used in organization.
These organizational approaches called “Database
models”.
27
Man power
Database
Payroll
Database
Employee
Data base

Types of Data Base models
 There are four types of database
models:
1. Hierarchical database model
2. Network database model
3. Relational database model
4. Object Oriented database model
28

Hierarchical Database model
- records are organized into hierarchy of
relationships (i.e.) parent and child
relationship.
- A parent record may have many child record.
But one child doesn’t have parent record
29
r1
r4
r3
r2
r5
r6

Network Database Model
 Network database model advanced than
hierarchical model; a set of record may
form network with the another set of
records
30
r1
r4
r3
r2
r5
r6

Relational Database model
 It is organized into a series of two dimensional
tables. The records are easy to access and
understand
31
R1 R5 R6 R7
R2 X Y Z
R3 X Y Z
R4 x y z

Object Oriented Database model
 It is bound together with its own data and a set of
instructions that describes the behavior and attributes of
the objects.
 Objects that have the same set of attributes and
methods are grouped into a class
 Objects use messages to interact with one another
 Object is described by a set of attributes
32
r1 r2 r3
Object 1 Object 2 Object 3

Advantages of Database
Management System
1. Data sharing is easy and available
2. Data redundancy reduced significantly
3. Improved data consistency
4. Database system keeps description of data separate from
applications (data independence)
5. Increased application programmer and user productivity
6. Improved data administration and control
7. Increased emphasis on data as a resource
33

Problems of Database system
1. Concurrency problems – Accessing the
database by multi-users simultaneously
2. Resource problems – requires extra
computing resources
3. Security problems – database must be
protected from the unauthorized access of
data
34

Query processing
 Query processing – procedure of transforming a high
level query (like SQL) into correct and efficient
execution plan expressed in low level language
 Performs the retrieval and manipulation in the
database
 A query processor select the most appropriate plan –
used in responding to a database
 SQL query processing requires DBMS to identify and
execute a strategy for retrieving the results of the
query
35

Steps in Query processing
 Step 1: Syntax analysis – SQL query
analyzed for syntax error
 Step 2: Query decomposition – phase of
query processing transform high level
query to machine level query
36

Pictorial diagram of query
processing
37
High level Query Language
Query Decomposer
Query optimizer
Query code Generator/ Query
Interpreter
Run time database
processor

 Query decomposer works in five stages:
1. Query analysis
2. Query normalization
3. Semantic analysis
4. Query simplifier
5. Query restructuring
Query optimizer – choosing an efficient execution
strategy for processing a query
38

Structured Query Language
 International standard language for creating or
manipulating relational databases
 SQL – special purpose programming
Language designed for managing data held in
a relational database management (RDBMS)
39

SQL Data Types
 Data types are:
1. CHARACTER(n)
2. CHARACTER
VARYING(n)
3. BIT
4. BIT VARYING(n)
5. NUMERIC (p , q)
1. DECIMAL (p , q)
2. INTEGER
3. SMALLINT
4. FLOAT (P)
40

SQL commands
 Lines of SQL codes – SQL application to perform
simple tasks against data inside of a database
Types of SQL commands:
1. Data definition language (DDL)
2. Data query Language (DQL)
3. Data Administration statements (DAS)
4. Data Manipulation Language (DML)
5. Data Control Language (DCL)
6. Transaction control statements (TCS)
41

1. Data Definition Language (DDL)
a. CREATE TABLE – statement used to create tables
to store data
Syntax:
CREATE TABLE table_name
(
Column_name1 Data_type
Column_name2 Data_type
);
(e.g.)
CREATE TABLE employee
(
Employee code Integer,
Name char(20)
Gender char(1)
);
42
Contd…

b. ALTER TABLE – used to change definitions of existing
tables
Used to add a column, add an integrity constraint, to
redefine a column (data type, size, default value)
Syntax:
ALTER TABLE table_name
ADD Column_name Data_typesize [constraint_name]
(e.g.) ALTER TABLE Employee
ADD (tel_number integer);
43
Contd…

c. DROP TABLE: command used to remove an
object from the database
once drop can’t get it back
Syntax:
DROP TABLE table_name
(e.g.) DROP TABLE Employee
44

Data Manipulation Language
 Users to insert data into database, modify and delete the data in
the database
 3 data manipulation commands:
a. INSERT statement – 2 ways to insert data into a table
1. Inserting data directly into a table
syntax:
INSERT INTO table-name[col-1,col-2,col-3… col-n]
VALUES (value-1,value-2,value-3….value-n);
(e.g.) INSERT INTO Employee
VALUES (015, ‘srinath’, ‘Aeronautics’)
45
Contd…

b. UPDATE Statement: UPDATE command specify the rows to
be changed using the WHERE clause and the new data using
the SET keyword.
syntax:
UPDATE table-name
SET Column_name = new-value
WHERE Column_name = some-value
(e.g.) UPDATE weather
SET average temp = 20 degree Celsius
WHERE City = ‘Madurai’
46
Contd…

 DELETE statement:
The SQL DELETE statement allows to delete a
single record or multiple records from a table
Syntax:
DELETE FROM table_name
WHERE Column_name = some_value
(e.g.)
DELETE FROM weather
WHERE city = ‘Nagpur’
47

Data query Language (DQL)
(c) This SQL statement enables the user to query one
or more table to get information they want.
1. SELECT Statement – used to select data from a
table.
Syntax: SELECT Column_name(s) FROM
table_name;
(e.g.) SELECT ______ FROM ______;
SELECT city FROM weather;
48
Contd…

(d) (DCL) Data control language:
- to prevent unauthorized access to data
1. GRANT 2.REVOKE
(e) Data Administration Statements (DAS):
- allows the user to platform audits and analysis on
operations within the database
(1) START AUDIT (2) STOP AUDIT
(f) Transaction control statements (TCS):
- manage all the changes made by the DML statements
(1) COMMIT (2) ROLLBACK (3) SAVEPOINT
49
Contd…

Aggregate functions
1. SUM() function – returns the total sum of a numeric
column
2. COUNT() function – allows to count the number of row in
a certain table
3. MIN() function – returns the smallest value of the selected
column
4. MAX() function – returns the largest value of the selected
column
50

 Advantages:
1. Portable
2. Easy to learn and
understand
3. Used with any DBMS
4. Interactive Language
5. Support Object based
Programming
• Disadvantages
1. Vendor variation
2. Join inconsistencies
3. Misconstructions in
WHERE
4. Complex grammar
51

Concurrency Management
 (Parallel) concurrency is a property of
systems in which several computations are
executing simultaneously
 When more than one user utilizes a
DBMS, problems can occur if the system is
not designed for multi users
 Concurrency problem –concurrency control
52

Reasons for concurrency Management
1. To improved throughput and resource utilization
2. To reduce waiting time
 Methods to avoid concurrency:
1. Locking file
2. Locking record
3. Locking data field
4. Versioning
53

Data Warehousing
 A data warehouse is a collection of
corporate information, derived directly
from operational system and some
external data sources.
 A data warehousing is subject oriented
integrated non volatile, time carrying
collection of data in support of its decision
making process.
54

Feature of data warehousing
1. Subject oriented
2. Integrity
3. Time variant
4. Non volatile
55

Architecture/structure of data
warehouse
 Data warehouse 3 tier:
1. Bottom tier – transaction processing
2. Middle tier – Analytical processing
3. Top tier – reporting, analysis and data
mining tools
56

Components of data warehouse
1. Data warehouse database:
a. Parallel relational database design
b. New indexed structure to bypass relational table
c. Multidimensional database
2. Sourcing, acquisition, clean up and transforming tools
a. Removing unwanted data
b. Converting to common data name and identification
c. Calculating summary and drive data
d. Establishing default for missing data
e. Accommodating source data definition changes
57
Contd…

3. Meta data:
data that describes the data warehouse
4. Access tools:
a. Query and reporting tools
b. Applications
c. Online analytical processing (OLAP)
d. Data mining
e. Data marts
f. Data warehouse administration and management
g. Information delivery system
58

Data Mart
 Partitions of overall data
warehouse
 Data marts provide the easiest
possible access to information
required by its user community
59

Characteristics:
1. Data mart aims to meet a department needs
2. A data warehouse spans the entire organization –designed using
enterprise data model
3. The data mart is easy to design, build and test
4. Contains only a small part of an organization’s data
5. Data warehouse needs to be planned and implemented as huge
projects
6. An organization can build many data marts independently
7. An organization can have different data marts – using different
design
8. No uniformity in data mart
9. Data mart source can be a data warehouse, data mart or OLTP
(Online transaction processing)
60

Types of data marts
1. Multidimensional database
data mart
2. Relational OLAP
61

Information Management unit 3 Database management systems

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