Query Efficiency: Select Only What You Need

The Problem with SELECT *

SELECT * retrieves ALL columns, even ones you don't need:

• More data transferred

• More memory used

• Harder to read and maintain

• Can break code if schema changes

  Better Practice

  Always specify the exact columns you need:

-- Instead of: SELECT * FROM users
SELECT id, username, email FROM users

Your Task

You need to create a user list showing only:

• username, email, created_at

  Write an efficient query using only these columns (not SELECT *).