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DBMS
(Questions and answers based on FIRST MODULE) 1.Define the term DBMS a) A database management system (DBMS) is a software package designed to define, manipulate, retrieve and manage data in a database. 2.A software package to facilitate the creation and maintenance of a computerized database is called ............ a) database management system (DBMS) 3.What is schema or database schema? a)A database schema is the skeleton structure of the database. It represents the logical view of the entire database 4.A view of a database that appears to an application program is known as ...... a) subschema 5.the data model which describe how the data is actually stored is knows as ...... a) intenal model 6.The level of dats abstraction which describes how the data is actually stored is known as....... a)physical level 7.The collection of information stored in a database at a particular mopment is called.... a)instance 8.What is data model? a)It is used to describe the structure of a database and basic operations on the database
- ........ level is both hardware and software independent a) conceptual
- ......... is the lowest level data model. a) physical data model 11.Data are............. a) Raw facts and figures
- DBA stands for..... a) Database Administrator 13.What is a database? a)A database is an organized collection of data, so that it can be easily accessed and managed. 14.What is a data? a)Data is a collection of a distinct small unit of information. It can be used in a variety of forms like text, numbers, media, bytes, etc. it can be stored in pieces of paper or electronic memory, etc. 15.What are the disadvantages of database system or DBMS? a)DBMS implementation cost is high compared to the file system Complexity: Database systems are complex to understand
Performance: Database systems are generic, making them suitable for various applications. However this feature affect their performance for some applications 16.What do you mean by data independence? a)Data Independence is defined as a property of DBMS that helps you to change the Database schema at one level of a database system without requiring to change the schema at the next higher level 17.Define logical data independance a)Logical data independence refers characteristic of being able to change the conceptual schema without having to change the external schema. 18.Define Physical data independance a)Physical data independence can be defined as the capacity to change the internal schema without having to change the conceptual schema. 19.Explain the advantages of DBMS over file systema
a) Drawbacks of File system
๏ Data redundancy: Data redundancy refers to the duplication of data, lets say we are managing the data of a college where a student is enrolled for two courses, the same student details in such case will be stored twice, which will take more storage than needed. Data redundancy often leads to higher storage costs and poor access time. ๏ Data inconsistency: Data redundancy leads to data inconsistency, lets take the same example that we have taken above, a student is enrolled for two courses and we have student address stored twice, now lets say student requests to change his address, if the address is changed at one place and not on all the records then this can lead to data inconsistency. ๏ Data Isolation: Because data are scattered in various files, and files may be in different formats, writing new application programs to retrieve the appropriate data is difficult. ๏ Dependency on application programs: Changing files would lead to change in application programs. ๏ Atomicity issues: Atomicity of a transaction refers to โAll or nothingโ, which means either all the operations in a transaction executes or none. ๏ Data Security: Data should be secured from unauthorised access, for example a student in a college should not be able to see the payroll details of the teachers, such kind of security constraints are difficult to apply in file processing systems.
Advantage of DBMS over file system
๏ No redundant data : Redundancy removed by data normalization. No data duplication saves storage and improves access time. ๏ Data Consistency and Integrity : As we discussed earlier the root cause of data inconsistency is data redundancy, since data normalization takes care of the data redundancy, data inconsistency also been taken care of as part of it ๏ Data Security : It is easier to apply access constraints in database systems so that only authorized user is able to access the data. Each user has a different set of access thus data is secured from the issues such as identity theft, data leaks and misuse of data. ๏ Privacy : Limited access means privacy of data.
Privacy : Limited access means privacy of data. Easy access to data : Database systems manages data in such a way so that the data is easily accessible with fast response times. Easy recovery : Since database systems keeps the backup of data, it is easier to do a full recovery of data in case of a failure. Flexible : Database systems are more flexible 22.What are the responsibilities of DBA and database designer? a) Responsibilities of a Database Administrator ๏ Software installation and Maintenance. A DBA often collaborates on the initial installation and configuration of a new Oracle, SQL Server etc database. ... ๏ Data Extraction, Transformation, and Loading. ... ๏ Specialised Data Handling. ... ๏ Database Backup and Recovery. ... ๏ Security. ... ๏ Authentication. ... ๏ Capacity Planning. ... ๏ Performance Monitoring. Responsibilities of a Database designers Write Programming Code Database designers write programming code, to create software, web applications, and database processes. Consolidate Data They consolidate data across multiple sources and databases to make it easier to locate and access. Design Online Forms These professionals design and implement online forms used for data collection and data processing. Program Automated Systems Database designers program automated data collection and data storage systems. Create and Enhance Data Models They also create new data models and enhance existing models to streamline data storage processes. Design Database Storage Systems Database designers design and implement database storage systems. Troubleshoot Database designers find potential problems within existing databases and programming codes and make recommendations to improve these systems. Analyze Data They also analyze existing data and database procedures to determine how much data is being stored and to assess the needs and capacity of current databases. 23.Explain the limitations of file system a) ๏ Data redundancy: Data redundancy refers to the duplication of data, lets say we are managing the data of a college where a student is enrolled for two courses, the same student details
in such case will be stored twice, which will take more storage than needed. Data redundancy often leads to higher storage costs and poor access time. ๏ Data inconsistency: Data redundancy leads to data inconsistency, lets take the same example that we have taken above, a student is enrolled for two courses and we have student address stored twice, now lets say student requests to change his address, if the address is changed at one place and not on all the records then this can lead to data inconsistency. ๏ Data Isolation: Because data are scattered in various files, and files may be in different formats, writing new application programs to retrieve the appropriate data is difficult. ๏ Dependency on application programs: Changing files would lead to change in application programs. ๏ Atomicity issues: Atomicity of a transaction refers to โAll or nothingโ, which means either all the operations in a transaction executes or none. ๏ Data Security: Data should be secured from unauthorised access, for example a student in a college should not be able to see the payroll details of the teachers, such kind of security constraints are difficult to apply in file processing systems. 24.Explain the three level architecture of DBMS a)
1. Internal Level
๏ The internal level has an internal schema which describes the physical storage structure of the database. ๏ The internal schema is also known as a physical schema. ๏ It uses the physical data model. It is used to define that how the data will be stored in a block. ๏ The physical level is used to describe complex low-level data structures in detail.
