What are advantages of DBMS over traditional file based systems?
Database management systems were developed to handle the following difficulties of typical file-processing systems supported by conventional operating systems.
1. Data redundancy and inconsistency
2. Difficulty in accessing data
3. Data isolation – multiple files and formats
4. Integrity problems
5. Atomicity of updates
6. Concurrent access by multiple users
7. Security problems
Q:- Explain the 3-tier architecture in DBMS.
or
What are the three different design levels of DBMS .
Three design of level DBMS are :-
1. External or View Level.
2. Conceptual or Logical Level
3. Internal or Storage Level.
External or View Level:-It is the user 's of the database. It is the highest level of abstraction. It deals with the way in which data is viewed by the individual users . The external view insulates users from the internal and conceptual view. Any number of users view even the identical ones may exist for the given conceptual or global view of the database.
Conceptual or Logical View :-It is the global view of the database. This level describes what data is stored in the database and the relationship among the data . It is the middle level in this 3-tier architecture. This level contain the logical structure of the entire database as seen by DBA.
Please note that there is always only one conceptual view per database. Entity Relationship Diagram we make is Conceptual View.
Internal or Storage View :- It is the physical representation of the database on the computer . This level describes how the data is stored in the database .It concerns with the way the data are physically stored on the hardware . It covers the data structure and files organization used to store data on storage devices. Please note that this internal level covers the physical implementation of the database to achieve optimal organization.
Following figure will make it more clear:-
Q:-Why do we need 3 level design for database and what are the two data independence ?
Ans:-The major objective of three level data independence is that if the changes are made at one level then upper are unaffected by it.
There are two type of data independence :-
1. Physical data independence:- It indicates that physical data storage structures or devices could be changed without affecting the conceptual schema .
2. Logical data independence :-It indicates that the conceptual schema can be changed without affecting the external level.
Q:- What is the difference between DBMS and RDBMS.
Relationship among tables is maintained in a RDBMS whereas this not the case DBMS as it is used to manage the database.
• DBMS accepts the ‘flat file’ data that means there is no relation among different data whereas RDBMS does not accepts this type of design.
• DBMS is used for simpler business applications whereas RDBMS is used for more complex applications.
• Although the foreign key concept is supported by both DBMS and RDBMS but its only RDBMS that enforces the rules.
• RDBMS solution is required by large sets of data whereas small sets of data can be managed by DBMS.
Database management systems were developed to handle the following difficulties of typical file-processing systems supported by conventional operating systems.
1. Data redundancy and inconsistency
2. Difficulty in accessing data
3. Data isolation – multiple files and formats
4. Integrity problems
5. Atomicity of updates
6. Concurrent access by multiple users
7. Security problems
Q:- Explain the 3-tier architecture in DBMS.
or
What are the three different design levels of DBMS .
Three design of level DBMS are :-
1. External or View Level.
2. Conceptual or Logical Level
3. Internal or Storage Level.
External or View Level:-It is the user 's of the database. It is the highest level of abstraction. It deals with the way in which data is viewed by the individual users . The external view insulates users from the internal and conceptual view. Any number of users view even the identical ones may exist for the given conceptual or global view of the database.
Conceptual or Logical View :-It is the global view of the database. This level describes what data is stored in the database and the relationship among the data . It is the middle level in this 3-tier architecture. This level contain the logical structure of the entire database as seen by DBA.
Please note that there is always only one conceptual view per database. Entity Relationship Diagram we make is Conceptual View.
Internal or Storage View :- It is the physical representation of the database on the computer . This level describes how the data is stored in the database .It concerns with the way the data are physically stored on the hardware . It covers the data structure and files organization used to store data on storage devices. Please note that this internal level covers the physical implementation of the database to achieve optimal organization.
Following figure will make it more clear:-
Q:-Why do we need 3 level design for database and what are the two data independence ?
Ans:-The major objective of three level data independence is that if the changes are made at one level then upper are unaffected by it.
There are two type of data independence :-
1. Physical data independence:- It indicates that physical data storage structures or devices could be changed without affecting the conceptual schema .
2. Logical data independence :-It indicates that the conceptual schema can be changed without affecting the external level.
Q:- What is the difference between DBMS and RDBMS.
Relationship among tables is maintained in a RDBMS whereas this not the case DBMS as it is used to manage the database.
• DBMS accepts the ‘flat file’ data that means there is no relation among different data whereas RDBMS does not accepts this type of design.
• DBMS is used for simpler business applications whereas RDBMS is used for more complex applications.
• Although the foreign key concept is supported by both DBMS and RDBMS but its only RDBMS that enforces the rules.
• RDBMS solution is required by large sets of data whereas small sets of data can be managed by DBMS.
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