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SQL Fundamentals · Database Basics · Lesson 3 of 17

Common Data Types

Concept

Common Data Types

INT stores whole numbers, VARCHAR stores variable-length text, and DATE stores calendar dates — picking the right type keeps data consistent.

By the end of this lesson
  • Explain the core idea behind Common Data Types.
  • Predict output before running a change.
  • Test one realistic and one unusual input.
  • Use the result to make the next decision.
How to study this page
  1. 1. Read one concept.
  2. 2. Change the example.
  3. 3. Run, compare, and explain.
  4. 4. Complete the challenge below.
ExampleRunnable
CREATE TABLE enrollments (
    id INT PRIMARY KEY,
    student_id INT,
    enrolled_on DATE
);
Try it Yourself »
Self-check before continuing

Without looking at the example, describe what changes when you modify one input in Common Data Types. Then reopen the editor and prove your explanation with a small test.

You are ready to continue when you can predict, test, and explain the result.

Your turn

Add a VARCHAR column for a status field to the enrollments table above.

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Console

Output will appear here...