Free ADC Data Retrieval & Query Techniques Questions and Answers

Question 1

What is the primary function of a SELECT statement in SQL?

Accepted Answer

Retrieve data from one or more tables.

Answer

The `SELECT` statement is the fundamental command in SQL used for querying and retrieving data from a database. It allows users to specify which columns and rows they want to view from one or more tables. Essentially, it's how you extract information stored within the database to display or use.

Question 2

Which clause is used to filter records in a SQL query?

Accepted Answer

WHERE

Answer

The `WHERE` clause in SQL is specifically used to filter records based on a specified condition. It allows you to retrieve only the rows that meet certain criteria, making your query results more precise and relevant. This is essential for narrowing down large datasets to find particular information.

Question 3

What does the JOIN operation accomplish in SQL?

Accepted Answer

Combines data from multiple tables based on a common field.

Answer

The `JOIN` operation in SQL is used to combine rows from two or more tables based on a common field between them. This allows you to retrieve a unified result set that contains data from all joined tables. It is crucial for working with relational databases where data is distributed across multiple interconnected tables.

Question 4

How can you sort data in ascending or descending order in SQL?

Accepted Answer

ORDER BY

Answer

The `ORDER BY` clause in SQL is used to sort the result set of a query. You can specify one or more columns to sort by, and choose between ascending (`ASC`) or descending (`DESC`) order. This helps in presenting data in a structured and easily understandable manner, making it easier to analyze.

Question 5

What is the result of using the DISTINCT keyword in a query?

Accepted Answer

Removes duplicate rows.

Answer

The `DISTINCT` keyword is used with the `SELECT` statement to eliminate duplicate rows from the result set. When applied, it ensures that each row returned is unique based on the values in the selected columns. This is particularly useful for obtaining a list of unique values or entries within a dataset.

ADC - Access Data Certification Practice Test

ADC - Access Data Certification Practice Test

Free ADC Data Retrieval & Query Techniques Questions and Answers