2nd Year Chapter 6 Table And Query Question-answer
Short and Simple Questions and Answers
Q1: What is a table?
Ans: A table is a fundamental object in a relational database, consisting of rows and columns. Each cell at the intersection of a row and column is called a cell, where data is stored. In a table, each row represents a tuple, and each column represents an attribute of an entity.
Q2: What is the degree of a relation?
Ans: The degree of a relation refers to the number of fields (columns) in a table. This degree is specified at the time of table creation and can be changed later. Changing the degree of a table may result in data loss.
Q3: What is the cardinality of a relation?
Ans: The cardinality of a relation is the number of records (rows) in a table. It can change as new records are added or existing records are deleted. For example, a table with 40 records has a cardinality of 40.
Q4: What are the two table views available in Microsoft Access?
Ans: Microsoft Access offers two table views: Design view and Datasheet view.
Q5: What is the Text data type?
Ans: The Text data type is the default data type in MS Access. It can store text or a combination of text and numbers, as well as numeric values that don’t require calculations (e.g., phone numbers). It has a size limit of 255 characters or the length set by the FieldSize property, whichever is less.
Q6: What is the Memo data type?
Ans: The Memo data type is used for fields that can contain more than 64,000 characters, making it suitable for storing long descriptions.
Q7: What is the Number data type?
Ans: The Number data type is used to store numeric data for mathematical calculations. It comes in various sizes, including 1, 2, 4, or 8 bytes (16 bytes if the FieldSize property is set to Replication ID).
Q8: What is the AutoNumber data type?
Ans: The AutoNumber data type assigns a unique sequential or random number to each record added to a table by Microsoft Access. AutoNumber fields cannot be updated, and they have a size of 4 bytes.
Q9: What is the use of Default value?
Ans: The Default value is used to set a default value for a field, especially when many records in a certain field have the same value. This eliminates the need to repeatedly enter the same value.
Q10: What is sorting?
Ans: Sorting is the arrangement of data in a particular sequence, which can be in ascending or descending order, based on a selected field or criterion.
Q11: What is referential integrity?
Ans: Referential integrity is a set of rules that ensures the validity of relationships between records in related tables. It prevents accidental deletion or modification of related data and requires that both tables have at least one common field with the same data type and size.
Q12: What is a query?
Ans: A query is a database object used to retrieve specific data from one or more tables. It can specify fields to display, conditions for data extraction, and relationships between tables.
Q13: What is a join?
Ans: A join is a query that extracts data from multiple tables based on the relationships between them. It combines data from different tables to provide meaningful results.
Q14: What are wildcards?
Ans: Wildcards are special symbols used in queries to search for data. Common wildcards include *, ?, and #, and they are typically used with fields of the Text data type.
Q15: Define criteria in a query?
Ans: Criteria in a query are conditions that limit the number of rows extracted from the database. They specify a set of rules for selecting records that meet certain criteria, allowing users to filter data as needed.