Short Answer Questions:
1. Define data and information.
Ans. Information is the processed form of data.
Data is the raw facts or observations.
2. Why is it not advisable to store a huge amount of data in files and folders?
Ans. When there is a huge amount of data involved, it is not advisable to store it in files and folders, since searching the data and retrieving it, becomes very time-consuming.
3. Why do we prefer using a database over using a spreadsheet, to store a huge amount of data?
Ans. Data in a database is arranged in such a manner, that data retrieval, data manipulation and data updating becomes very easy.
Moreover, spreadsheets prove to get slow, when a massive amount of data is involved, so the use of a database is preferred.
4. Define a database.
Ans. A database is an organised collection of data, generally stored and accessed electronically, from a computer system. Data in a database is so arranged, that data retrieval, data manipulation and data updating becomes very easy.
5. What is a database management system?
Ans. A Database Management System (DBMS) is a collection of programs, which enables its users to access the database, manipulate the data and prepare reports for the presentation of data.
6. Define data redundancy.
Ans. When the same piece of data is present at two or more different places, it is called data redundancy
7. Define data inconsistency.
Ans. When different versions of the same data appear at different places, it is called data inconsistency.
8. Define data integrity.
Ans. Data integrity is having correct and accurate data in the system.
9. Explain the structure of a hierarchical database.
Ans. A Hierarchical database model has the data organised into a tree-like structure with nodes representing records and branches representing fields. It allows one-to-many relationships, but does not support many-to-many relationships.
10. Explain the structure of a Network database model.
Ans. A network database allows more than one parent node. This database model can represent one-to-many and many-to-many data relationships. As the data is more related, hence accessing the data becomes easier and faster.
11. How is data stored in a Relational database?
Ans. In a relational database, the data is organised in a two-dimensional table and the relationship between the tables is maintained by storing a common field. The tables are also known as relations in a relational model.
12. What is a primary key? What are its features?
Ans. In a relational database, a primary key is a special table column (a field), which uniquely identifies all the table records. A primary key's main features are:
- It must contain a unique value for each row of data.
- It cannot contain null values.
- Every row must have a primary key value.
- A relational database cannot have more than one primary key.
13. What is a candidate key?
14. How is a database management system better than file system.
Ans. Database management is a centralised system of data storage so it reduces the chances of data redundancy, data inconsistency and increases data integrity and validation.
Application Based Question:
Which field would you recommend for being a primary key in a relational database having records of:
(a) employees of an organisation?
(b) books in a library?
(c) customers of a mobile company?
(d) eligible voters of an area?
(e) flight details of people travelling to foreign countries?
Ans. (a) Employee id can be used as the primary key, as every employee is assigned a unique id, by every organisation.
(b) Accession number can be used as the primary key, as it is unique for every book.
(c) No two customers can have the same phone number, so phone number can be used as the primary key.
(d) Every voter is assigned a unique voter id, which can be used as the primary key.
(e) Passport number is the best field to be assigned as the primary field, as it is unique for every person, all over the world.
Short Answer Questions:
1. What is the difference between Char and Varchar datatype?
Ans. CHAR is used for a fixed length string for which fixed amount of memory is reserved. For CHAR(30) even if the input is 5 characters, the memory will still be reserved for 30 characters. Variable character string-The memory reserved depends on the length of the string entered. It varies with each input. If input is 5 characters then memory will be reserved for 5 characters only.
2. What happens if we register a database?
Ans. When a database is registered it gets registered with LibreOffice base and other users can also access it.
3. If a field has to be declared as primary key, what are the conditions to be taken care of?
Ans. The field set as primary key must have always have a value and that value should be a unique value for each record.
4. What are the two ways to create a table?
Ans. A table can be created using Table Wizard and Design View.
5. What does the Description pane in the design view hold?
Ans. The Description pane allows the user to write anything significant about the field. It does not form a part of the database or table.
6. How can we make a primary key of multiple fields?
Ans. To make a primary key consisting of multiple fields i.e. composite key, select the fields keeping the Ctrl key pressed. Once the required fields are selected, Right-click on any of the selected fields and select Primary Key from the pop-up menu.
7. Write the steps to sort the data in a table according to the primary key field.
Ans. The steps for sorting data in a table are:
- 1. Open the table to be sorted.
- 2. Click Data. Choose Sort Ascending if the table has to be sorted according to the primary key, Sort Descending if table has to be sorted in descending order.
- 3. There is a third option Sort which gives us a dialog box. In case we want to sort on multiple fields we can set the fields in this dialog box.
- 4. Sorting can also be done from the toolbar that displays icons for Sort, Sort Ascending and Sort Descending
Application Based Questions:
1. Which data type would you recommend for the following fields of a record?
(a) First name
(b) Middle name(e) Married
(f) Pincode(h) Mobile number
(j)Salary
(j) Date of Birth(k) Address
(1) Picture
(m) song
ANSWER
(a), (b), (c), (d) varchar
(e) Boolean
(f) Integer
(g) Integer
(h) Integer
(i) Decimal-currency
(j) Date
(k) Varchar
(1) Longvarbinary
(m) Longvarbinary
2. Gaurav has created a database in which a table has the description, as the data, in one of the fields. What should be the data type of this field?
Ans. The data type should be memo for a field, with descriptive data.
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