DISTINCT and Aliases

SQL gives you tools to clean up your results and rename columns to make your output easier to read and work with.

The DISTINCT keyword removes duplicate values, and the AS keyword gives aliases to columns or tables.

The DISTINCT keyword is used in the SELECT clause to return only unique values.

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SELECT DISTINCT title
FROM book_checkouts;

If the same book has been checked out multiple times, this will show each title only once.

The AS keyword allows you to assign an alias, a temporary name, to a column or table in your query.

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SELECT title AS book_title, member_id AS borrower
FROM book_checkouts;

In the result, column headers will appear as book_title and borrower instead of title and member_id.

These tools help you:

• Eliminate unnecessary repetition
• Clean up the structure of your results
• Make reports and queries more readable

Aliases are especially useful when working with:

• Long or complex column names
• Joining multiple tables with overlapping names

You've now learned the core SQL tools. Next up: a Final Quiz to test your understanding of SQL Basics!