Database Basic Questions for Practice
Q 1.What is the Database?
Ans:
A database is a collection of information that is organized in such a way that it can be easily accessed, managed and updated.
Q 2.What is DBMS?
Ans:
A DBMS or DataBase Management System is software application that helps users in handling the storage, retrieval, and updating of data in a computer system. It helps to manage large volume of data.
Q 3.What is RDBMS?
Ans:
RDBMS or Relational DataBase Management System is a database which stores information in relational format or tables. E.g. Oracle, MYSQL, MSAccess, Sybase etc.
Q 4.What are advantages of DBMS?
Ans:
The advantages of DBMS are
- Avoids Data redundancy or duplication of data
- Allows Data Independence
- It allows sharing of data.
- It removes data inconsistency hence ensures data Integrity is maintained.
- It provides enhanced security through authorization, passwords etc.
Q 5.What is data redundancy?
Ans:
Data redundancy means duplication of data. Non-database systems maintain separate copy of
data for each application. This duplication of data may lead to inconsistency or incorrect data at times. DBMS stores all data at one place and all the application programs that require this data can refer to the same central place. This centralization makes sure, that data remain consistent and secure.
Q 6.What is the Table? Or what are the components of table.
Ans:
A table is data set that is organized into rows and columns. A row is also called as record which represents one complete unit of information. Columns are also called as Fields which contains one type of information.
Q 7.What is Record?
Ans:
Records are the rows representing one complete unit of information. A logical record contains contents of all the fields. A database may have many records.
Q 8.What is Data Item or Field?
Ans:
A data item or Field is the column containing one type of information. It is the smallest unit of named data. It may consist of any number of bits or bytes.
Q 9.What is a Data Type?
Ans:
A data type is type of data that is stored in a field, it can be character, number, image etc.
Q 10.What is Primary Key?
Ans:
Primary key is a field which uniquely identifies each record in the table. A table can have only one primary key and this key cannot be empty.
Q 11.What are 3 levels of structure of DBMS?
Ans:
The structure of DBMS is divided into 3 levels.
- External Level
- Conceptual Level
- Internal Level
Q 12.What is the difference between external, Conceptual and internal level of database structure?
Ans:
Database structure is divided into 3 levels.
| External Level | Conceptual Level | Internal Level |
|---|---|---|
| It is also called as user view and is the highest level | It is the intermediate level | This is the lowest level |
| Allows access to only portions of database which concerns the user. | It describes the detail of all information that is kept and relationship between them. | It describes how data will be stored. It describes the data structure and access methods. |
Q 13.What is data Independence?
Ans:
Data independence means it is possible to change the storage structure or records and relations without affecting the applications
Q 14.What are different types of DBMS users?
Ans:
Different types of DBMS users are
| Passive Users | Online Users | Application Programmers | Database administrators |
|---|---|---|---|
| Users not aware of database system | Users are aware of database system | Professional programmers with good knowledge of database | In depth knowledge of database and people who manage the database |
| Need to be instructed to carry out a transaction | Can carry out direct communication with database. | Write application programs in Java, C++ to control databases | Responsible to create & maintain database. Also recover database in case of failure. |
| e.g. ATM user. | e.g. online banking/trading users. | e.g C++ programmer. | e.g. MySQL Administrator |
Q 15.What is the difference between DDL and DML?
Ans:
| DDL (Data Definition Language) | DML (Data Manipulation Language) |
|---|---|
| It is a language used for defining data in the database | Language used for manipulating data in a database |
| Used for creating, modifying, and deleting TABLES in the database. | It provides commands to select and retrieve data from the database. |
| e.g. CREATE, ALTER, DROP TABLES. | e.g. INSERT, UPDATE, DELETE,SELECT |
Q 16.What are major components of DBMS?
Ans:
Major components of DBMS are
- DDL Compiler: It converts data definition statements into set of tables
- Data Manager: IT is the database control system which maintains and secures data. It interfaces with file system
- File Manager: It is responsible for maintaining the structure of files and managing the file space. It interfaces between Data and disk manager and coordinates between them.
- Disk Manager: It performs all input and output operation on the storage disk. It saves/returns block of pages requested by file manager.
- Query Processor: It interprets online user queries
- Telecommunication System: Online user communicates by sending and receiving messages over communication system.
- Data Dictionary: Information about structure and usage of data contained in database is maintained in data dictionary.
Q 17.Give full form of following?
Ans:
DDL: Data Definition Language.
DML: Data Manipulation Language.
DBMS: Data Base Management System.
RDBMS: Relational Database management system.
DBA: Data Base Administrator
ATM: Automated Teller Machine.
Q 18.Fill in the blanks
- ______________ is responsible for managing and maintaining the database management system.
Ans. DBA: Data Base Administrator
- ______________ contains information about structure and usage of data contained in database.
Ans. Data Dictionary.
- ______________ is a type of data base system which stores data in tables
Ans. RDBMS (Relational Database)
- ______________ is a row in database giving one full unit of information
Ans. Record
- ______________, ____________ and ____________are three levels of database
Ans. External, Conceptual, Internal
- ______________ means it is possible to change the storage structure of database without affecting the applications.
Ans. Data Independence
- ______________ is a field which uniquely identifies as each record in a table
Ans. Primary Key
- ______________ is an example of an RDBMS
Ans. MS Access, MSSQL, Oracle, PostgreSQL.
- DROP, ALTER are example of ______________ type of database command.
Ans. DDL, Data Definition language.
- INSERT, SELECT are example of ______________ type of database command.
Ans. DML, Data Manipulation language.
- _____________converts data definition statements into set of tables.
Ans. DDL Compiler.
- The disk manager performs _____________and _____________ operations.
Ans. DDL Compiler.
- _____________part of DBMS is responsible to maintain the structure of files and managing file space.
Ans. File Manager.
- _____________is the lowest level of database implementation.
Ans. Internal.
- _____________interprets online user query.
Ans. Query Processor.
- _____________and ___________ are example of DDL Command.
Ans. CREATE, ALTER, DROP TABLES.
- _____________and ___________ are example of DML Command.
Ans. INSERT, UPDATE, DELETE, SELECT
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