Deals Of The Week - hours only!Up to 80% off on all courses and bundles.-Close

Wrap course as a gift

Prepare your gift and double-check it looks just right.

Form validation errors

Recipient's Name:
Recipient's Email:
Your Message (Optional):
Proceed to Checkout

Creating Tables in SQL

Introduction
UNIQUE
NOT NULL
15. NULL columns
CHECK
DEFAULT
Summary

Instruction

And... success. We did not specify that the columns were NOT NULL, so we could leave them without a value. In other words, if a column doesn't have the NOT NULL constraint, its value can be a NULL.

If you want, you can stress the fact that a certain column can be NULL by writing the keyword NULL after the column type:

CREATE TABLE rpg_game (
    id IDENTITY PRIMARY KEY,
    name varchar(32) UNIQUE NULL,
    genre varchar(32),
    classes_no int,
    complexity int,
    min_players int
);

The above code would work just as well without the NULL keyword. Its point is to draw the reader's attention to the fact that a column is NULLable.

Exercise

We've added the keyword NULL to every column in the table rpg_game except for the id column. Take your time and try to add a few rows without some of the NULLable columns. Observe what happens.