Column Aliases with AS

Sometimes column names aren't clear or you want to rename them in your output. Aliases let you give columns temporary names.

The AS Keyword

SELECT column_name AS alias_name FROM table_name;

The alias only affects the output - it doesn't change the actual column name in the database.

Exercises

Optional AS Keyword

In many SQL databases, the AS keyword is optional:

-- These are equivalent:
SELECT name AS username FROM users;
SELECT name username FROM users;

However, using AS makes your queries more readable.

Common Use Cases for Aliases

Aliases are helpful when:

• Column names are cryptic (e.g., usr_nm becomes user_name)
• You're doing calculations (e.g., price * quantity AS total)
• Column names would conflict in joins
• You want clearer output for reports

Free Practice

Experiment with:

• Aliases without the AS keyword
• Aliases with special characters (use double quotes)
• Mixing aliased and non-aliased columns