DISTINCT and Aliases
SQL provides tools to clean your results and make column names easier to read.
The DISTINCT keyword removes duplicate values, while the AS keyword assigns temporary names — called aliases — to columns or tables.
DISTINCT: Remove Duplicate Values
The DISTINCT keyword is used in the SELECT clause to return only unique values.
Remove duplicate book titles
SELECT DISTINCT title
FROM book_checkouts;
If the same book has been checked out multiple times, this will show each title only once.
AS: Rename Columns and Tables
The AS keyword allows you to assign an alias, a temporary name, to a column or table in your query.
Rename columns for clarity
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.
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