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Class 9 Computer Science Chapter 6 Database
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Chapter – 6
Important Terms (Basic Concepts)
Database (PART – I)
● Database: A collection of related information organised as tables is known as database.
● Table: A table in a database is a structure to store a set of data with common attributes.
● Field: Each attribute in a table is called fields and used as columns of the table.
● Record: Data is stored in a table in terms of rows by putting values for every column. Each row in a table is called a record.
● Redundancy: Redundancy means having multiple copies of same data in the database.
● Query: A query is a simple question that you ask to find some specific information from the database.
● Form: A form provides an interface that allows users to enter, change and view the data in a database table.
● Report: Report are used to present data from tables or queries in a format that can be printed.
TEXTUAL QUESTIONS AND ANSWERS
OBJECTIVE TYPE QUESTIONS
1. Choose the correct option.
(a) DBMS is a
(1) Type of database
(2) Set of computer programs
Ans. (1) Type of database.
(b) Which of the following key composed of additional fields?
Ans. (4) Alternate.
(c) Which option is used change the appearance and size of various controls of a Form?
(1) Design View
(2) Form View
(3) Layout View
(4) None of these
Ans. (1) Design View.
(d) Which key defines a relationship between two tables?
(1) Primary key
(2) Candidate key
(3) Secondary key
(4) None of these
Ans. (1) Primary key.
(e) Which icon indicates the edit mode in Access?
(4) None of these
Ans. (3) Pencil.
2. Fill in the blanks.
(a) In ____ database data are stored in multiple tables to remove redundancy.
(b) A candidate key is called ___ key, if it is not designated as primary key.
(c) Microsoft Access is a _____ database.
(d) ____ view displays the table as grid.
(e) ____ allows you to add and update data in a table, one record at a time.
DESCRIPTIVE TYPE QUESTIONS
3. Short answer questions.
1. What is Database? Give examples.
Ans. A database is a systematic collection of structured information or data, typically stored electronically in a computer system. In a database, dada is organised in such a way that it can be easily accessed and managed.
2. What is the need for database?
Ans. The various reasons a database is important are :
Manages large amounts of data: A database stores and manages a large amount of data on a daily basis. This would not be possible using any other tool such as a spreadsheet as they would simply not work.
Accurate: A database is pretty accurate as it has all sorts of build in constraints, checks etc. This means that the information available in a database is guaranteed to be correct in most cases.
Easy to update data: In a database, it is easy to update data using various Data Manipulation languages (DML) available. One of these languages is SQL.
Security of data: Database have various methods to ensure security of data. There are user logins required before accessing a database and various access specifiers. These allow only authorised users to access the database.
3. Define: primary key, Foreign key, Candidate key, Super key.
Ans. Primary key – Primary key is a column or group of columns in a table that uniquely identify every row in that table.
Foreign key – Foreign key is a column that creates a relationship between two tables. The purpose of Foreign keys is maintain data integrity and allow navigation between two different instances of an entity.
Candidate key – Candidate key is a set of attributes that uniquely identify each row in a table. Candidate key is a super key with no repeated attributes.
Super key – A super key is a group of single or multiple keys which identifies rows in a table.
4. Differentiate between Flat file database and Relational database.
Ans. The difference between flat file database and Relational database are:
|Flat File Database||Relational Database|
|(1) Contains only one table.||(1) Contains more than one table where relationship exist between the data in the table.|
|(2) A flat file database often suffers from inefficient repetition of data.||(2) Relational database removes duplication of data by creating relationship from them.|
5. What are data types? List the various types of data types used in Access 2007 and explain any four of them.
Ans. Data type determines what kind of data it can store. MS Access supports different types of data, each with a specific purpose. The data type determines the kind of the values that users can store in any given field.
THE FOLLOWING ARE THE AVAILABLE DATA TYPES IN ACCESS 2007
|(1) Auto Number.||(1) An Auto Number field creates unique values automatically when Access creates a new record.The Auto Number field is primarily used for Primary keys in Access.|
|(2) Text.||(2) A Text field can contain values that are text, numeric or a combination of both. A text field can contain a maximum length 255 characters.|
|(3) Memo.||(3) A mush larger version of the text field, allowing storage of up 2 GB of data.|
|(4) Number.||(4) The Number field can store numeric values up to 16 bytes of data.|
|(5) Data/time.||(5) The Data/Time field allows storage of and time information.|
|(6) Currency.||(6) The Currency data type stores values in a monetary format. This can be used with financial data as 8-byte numbers with precision to four decimal places.|
6. What is a query? Explain the parts of a query window.
In general, a query is a simple question that you ask to find some specific information from the database. In Access, when you build a query, you are defining specific conditions.
In other words, Queries allow you to retrieve information from one or more tables based on a set of search conditions you define. Queries are made on tables and the results are displayed in the form of table, i.e., in a group of rows and columns with the set of records that match the given condition.
The table selected for query will appear as a small window in the upper section of the Query window i.e., the Object Relationship Pane.
The field name that will be added in the query will be done in the bottom section of the Query window i.e., Design Grid.
7. What do you understand by criteria?
Ans. This property contains the condition on the basis of which the records will be filtered in the Query output.
ADDITIONAL QUESTIONS AND ANSWERS
1. What is database?
Ans. A collection of related information organised as tables is known as database, e.g. MS-Access, MySQL etc.
2. Define DBMS.
Ans. Database Management System (DBMS) is a software that enable its users to search, insert, updated and delete data.
3. What does RDBMS Stands for?
Ans. RDBMS Stands for Relational Database Management System.
4. Define tables, fields, records.
Ans. A table in a database is a structure to store a set of data with common attributes. Each attribute in a table is called fields and used as columns of the table.
Data is stored in a table in terms of rows by putting values for every column. Each row in a table is called a record.
5. Write the relationship between a database and a table.
Ans. A database contains multiple tables whereas, a table cannot exist outside a database.
6. What is use of DBMS?
Ans. DBMS is used to provide a convenient and efficient environment in which we can store and retrieve information.
7. Define primary key with an example.
Ans. A field which uniquely identifies each record in a table is known as primary key. e.g. Stdid is the primary key of the Student table.
8. What is the significance of a primary key?
Ans. A primary key cannot allow null values and must have a unique index.
9. Write the significance of a foreign key.
Ans. A foreign key is used to establish relationship between any two tables of RDBMS.
10. State the relationship and difference between a primary and foreign key.
Ans. Primary key and Foreign key are used to relate the tables so that data can be fetched from multiple tables.
We cannot enter duplicate values in Primary key while duplicate values can be entered in Foreign key.
11. Define query in the context of database.
Ans. A query is an inquiry into the database using the SELECT statement. These statements give you filtered data according to your conditions and specifications indicating the fields, records and summaries which a user wants to fetch from a database.
12. Define forms and what is the need of using them?
Ans. In a database, a form is a window or screen that contains numerous fields or spaces to enter data. Forms can be used to view and edit your data. It is an interface in user specified layout. e.g. a user can create a data entry from that looks exactly like a paper form. People generally prefer to enter data into a well – designed from, rather than a table.
13. What do you understand by report?
Ans. When you want to print those records which are fetched from your database, design a report. It is an effective way to present data in a printed format. It allows you to represent data retrieved from one or more tables, so that it can be analysed.
14. Define RDBMS.
Ans. RDBMS is a type of Database Management System that stores data in the form of relations (tables).
15. Distinguish between a record and a field in a table.
Ans. The difference between record and a field are:
|(1) It is a collection of data items, which represent a complete unit of information about a thing or a person.||(1) It is an area within the record reserved for a specific piece of data.|
|(2) A record refers to row in the table.||(2) A field refers to a column in the table.|
|(2) Record is also known as tuple.||(3) Field is also known as attribute.|
16. What is the purpose of using queries?
Ans. The purpose of using query is to collect specific information from the pool of data (TABLE). A query also helps us to extract information from different tables.
17. Differentiate between forms and reports.
Ans. The difference between forms and reports are:
|(1) A form provides an interface that allows users to enter, change and view the data in a database table.||(1) Reports are used to present data from tables or queries in a format that can be printed.|
|(2) We can make changes to data.||(2) We cannot make changes to the data.|
18. What is MS – Access?
Ans. Microsoft Access is the most popular RDBMS that comes as a part of the Microsoft Office Suite. It is a database management system (DBMS) that combines the relational Microsoft Jet Database Engine with a graphical user interface and software-development tools.
19. What are the uses of MS – Access?
Ans. Following are the major uses of MS Access:
● Manage accounts and bills.
● Store data in the form of tables and edit or customise them later as per the requirement of the user.
● It can be used to make our websites.
● Comparing data or finding a relationship between the existing data can be done using Access.
20. Define macro and modules in database.
Ans. A macro in Access is a tool that allows you to automate tasks and add functionality to your forms, reports, and controls.
A module is a collection of declarations, statements, and procedures that are stored together as a unit.
21. What is the difference between datasheet view and design view?
Ans. Datasheet view allows us to view, add, edit, and delete records.
This Design View allows us to create and modify a table’s design by specifying the fields it will contain, the fields’ data types, and their associated properties.
22. What are the rules for naming a field in MS Access?
Ans. Following are the rules for naming a field.
● A field name can range from 1 to 64 characters.
● A field name can include letters, numbers and some special characters. Generally, the underscore (_) sign is used.
● A field name cannot start with a blank space.
● A field name cannot have a period (.), exclamation (!) or brackets () .
23. What are the different types of views in which a report can be displayed?
Ans. Report view – You can view data of the report in this view but cannot make modification in the design.
Print preview – This view allows you to see how the report will look when printed.
Layout view – It provides a view that closely resembles what the report will actually look like to the user.
Design view – This view displays only the structure of the report which can be modified and customised as per requirement.
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