lOMoAR cPSD| 46941280
Database Management Systems – 22319 C0-31
Unit – I: Database System Concepts
Course Outcomes (COs):
• Design normalized database on given data.
Unit Outcomes (UOs):
• State the importance of DBMS over file processing in the given situation.
• Describe the overall structure of the given DBMS
• Identify the relevant database model in the given situation.
• Draw the E-R diagram of the given database and identify relationship between the
entities.
1.1 Data:
• Data is nothing but the information which is having implicit meaning.
• Data is a set of values of qualitative or quantitative variables about one or more objects.
• It is facts and statistics collected together for reference or analysis.
1.2 Database:
• A database is a collection of information that is organized so that it can be easily
accessed, managed and updated.
1.3 Database Management System (DBMS):
• A database management system (DBMS) is system software for creating and
managing databases. A DBMS makes it possible for end users to create, read, update
and delete data in a database.
1.4 Primary Goal of Database Management System:
• Primary goal of database management system is to provide a way to store and
retrieve database information that is convenient and efficient.
• Management of data involves both defining structure for storage of information and
providing mechanism for manipulation of information.
1-1
, lOMoAR cPSD| 46941280
Database Management Systems – 22319 C0-31
1.5 Services provided by DBMS:
1. Define the structure. (Creation of Database)
2. Manage the storage.
3. Manipulate the database. (Insert, Update, Delete, etc. from/into Database)
4. Manage database usage. (Give rights to users to access database and optimize process)
5. Monitor and analyze database usage.
6. Performing tuning and maintenance of database.
1.6 Application Areas of Database Management System:
Sector Use of DBMS
Banking For customer information, account activities, payments, deposits,
loans, etc.
Airlines For reservations and schedule information.
Universities For student information, course registrations, colleges and grades.
Telecommunication It helps to keep call records, monthly bills, maintaining balances,
etc.
Finance For storing information about stock, sales, and purchases of
financial instruments like stocks and bonds.
Sales Use for storing customer, product & sales information.
Manufacturing It is used for the management of supply chain and for tracking
production of items. Inventories status in warehouses.
HR Management For information about employees, salaries, payroll, deduction,
generation of paychecks, etc.
1.7 Disadvantages of File Processing System:
1.7.1 Data redundancy and inconsistency:
• The data files and application programs are created by different programmers over a
long period.
• The data files are likely to have different formats.
• Programs may be written in several programming languages.
• The same information may be duplicated in several files.
1-2
, lOMoAR cPSD| 46941280
Database Management Systems – 22319 C0-31
• Example: Information of student like roll number, class, division, name, etc. is
repeated in student details file system and library details file system.
• Duplication of data results in data redundancy.
• Data redundancy increases the cost of storing and retrieving the data.
• If some update is done on these database and if the values of these common fields are
not matching for some records in both files, then it results in inconsistent data.
1.7.2 Difficulty in accessing data:
• Conventional file processing system does not allow required data to be retrieved in
convenient and efficient manner.
• Example:
• This makes accessing of data difficult.
1.7.3 Data isolation:
• As data is scattered in various files and files may be in different format and different
location, it is difficult to write new application program to retrieve appropriate
information.
1.7.4 Integrating problem:
• The data stored in database must satisfy certain type of consistency constraints.
• Example: Suppose University maintains results records for various departments.
University may require that the percentage data to be between 0 – 100. Developers will
add constraints by adding appropriate code in the application programs which will
check if marks are entered in proper range.
• But, when the new constraints are added, it is difficult to change the program to enforce
them.
1.7.5 Atomicity problem:
• A computer system like any other device is subject to failure.
• In many applications, it is crucial that if a failure occurs the data be stored to consistent
state that existed prior to failure.
• Example: A transaction is a monetary transfer from Account A to B. It consists of
operations such as withdrawing from A and depositing to B. But during this process,
there is a power failure for few seconds and transaction is terminated. It may happen
that amount is withdrawn from A but not deposited in B.
• This is atomicity problem.
1-3
Database Management Systems – 22319 C0-31
Unit – I: Database System Concepts
Course Outcomes (COs):
• Design normalized database on given data.
Unit Outcomes (UOs):
• State the importance of DBMS over file processing in the given situation.
• Describe the overall structure of the given DBMS
• Identify the relevant database model in the given situation.
• Draw the E-R diagram of the given database and identify relationship between the
entities.
1.1 Data:
• Data is nothing but the information which is having implicit meaning.
• Data is a set of values of qualitative or quantitative variables about one or more objects.
• It is facts and statistics collected together for reference or analysis.
1.2 Database:
• A database is a collection of information that is organized so that it can be easily
accessed, managed and updated.
1.3 Database Management System (DBMS):
• A database management system (DBMS) is system software for creating and
managing databases. A DBMS makes it possible for end users to create, read, update
and delete data in a database.
1.4 Primary Goal of Database Management System:
• Primary goal of database management system is to provide a way to store and
retrieve database information that is convenient and efficient.
• Management of data involves both defining structure for storage of information and
providing mechanism for manipulation of information.
1-1
, lOMoAR cPSD| 46941280
Database Management Systems – 22319 C0-31
1.5 Services provided by DBMS:
1. Define the structure. (Creation of Database)
2. Manage the storage.
3. Manipulate the database. (Insert, Update, Delete, etc. from/into Database)
4. Manage database usage. (Give rights to users to access database and optimize process)
5. Monitor and analyze database usage.
6. Performing tuning and maintenance of database.
1.6 Application Areas of Database Management System:
Sector Use of DBMS
Banking For customer information, account activities, payments, deposits,
loans, etc.
Airlines For reservations and schedule information.
Universities For student information, course registrations, colleges and grades.
Telecommunication It helps to keep call records, monthly bills, maintaining balances,
etc.
Finance For storing information about stock, sales, and purchases of
financial instruments like stocks and bonds.
Sales Use for storing customer, product & sales information.
Manufacturing It is used for the management of supply chain and for tracking
production of items. Inventories status in warehouses.
HR Management For information about employees, salaries, payroll, deduction,
generation of paychecks, etc.
1.7 Disadvantages of File Processing System:
1.7.1 Data redundancy and inconsistency:
• The data files and application programs are created by different programmers over a
long period.
• The data files are likely to have different formats.
• Programs may be written in several programming languages.
• The same information may be duplicated in several files.
1-2
, lOMoAR cPSD| 46941280
Database Management Systems – 22319 C0-31
• Example: Information of student like roll number, class, division, name, etc. is
repeated in student details file system and library details file system.
• Duplication of data results in data redundancy.
• Data redundancy increases the cost of storing and retrieving the data.
• If some update is done on these database and if the values of these common fields are
not matching for some records in both files, then it results in inconsistent data.
1.7.2 Difficulty in accessing data:
• Conventional file processing system does not allow required data to be retrieved in
convenient and efficient manner.
• Example:
• This makes accessing of data difficult.
1.7.3 Data isolation:
• As data is scattered in various files and files may be in different format and different
location, it is difficult to write new application program to retrieve appropriate
information.
1.7.4 Integrating problem:
• The data stored in database must satisfy certain type of consistency constraints.
• Example: Suppose University maintains results records for various departments.
University may require that the percentage data to be between 0 – 100. Developers will
add constraints by adding appropriate code in the application programs which will
check if marks are entered in proper range.
• But, when the new constraints are added, it is difficult to change the program to enforce
them.
1.7.5 Atomicity problem:
• A computer system like any other device is subject to failure.
• In many applications, it is crucial that if a failure occurs the data be stored to consistent
state that existed prior to failure.
• Example: A transaction is a monetary transfer from Account A to B. It consists of
operations such as withdrawing from A and depositing to B. But during this process,
there is a power failure for few seconds and transaction is terminated. It may happen
that amount is withdrawn from A but not deposited in B.
• This is atomicity problem.
1-3
