Class-8th Ch-2 Working with RDBMS

Chapter- 2 Working With RDBM

A. Answer the following questions in short . 

Q.1    What is a primary key?

Ans:-     A primary key is a field that uniquely identifies each record in a table.

Q.2    Name 3 data types stored in a database.

Ans:-    1. Text  2. Number  3. Date/Time 

Q.3    What file extension does MS Access 2007 use for databases?

Ans:-    MS Access uses the .accdb  file extension for databases.

Q.4    What do you use Table Design View for?

Ans:-    Table Design View allows to design the table structure like fields, properties, primary keys, etc.

Q.5     What can you do in Datasheet View?

Ans:-    Table datasheet view allows viewing, inserting and editing of table data.  

B.     Answer the following questions in long. 

Q.1       What is a table ? How is it different from a query ? 

Ans:-      A table stores raw data in rows and columns. A query searches or filters that data based on conditions to show specific results. Tables hold data, while queries retrieve and display selected data from tables.

Q.2        Why do we need to relate the tables ?  

Ans:-     We relate tables to avoid duplicate data, ensure accuracy, and maintain consistency. Relationships link related information across tables, enforce referential integrity, and help retrieve complete data efficiently without repetition or errors.

Q.3    What is the role of criteria in a query ? Give an example.

Ans:-    Queries are used to search, filter, and retrieve specific data from a database. Criteria in a query filters data to show only records that meet specific conditions. It helps retrieve exact information needed.

Example -  In a Student table, criteria Class = "5" will show only class 5 students.

Q.4     What do you mean by referential integrity?

Ans:-  Referential integrity keeps table links correct. The foreign key must match a primary key in another table. This stops bad or missing data and keeps records connected properly.

Q.5    Write one difference and one similarity between primary key and foreign key . 

Ans:-    Similarity-      Both primary key and foreign key are used to create links between tables in a database. 

Difference-     A primary key uniquely identifies each record in its own table and cannot be duplicate or null, while a foreign key refers to a primary key in another table and can have duplicates or null values.