Create Table: How to Set NOT NULL

Here’s sample SQL query for how to write NOT NULL column constraint correctly. Before you go into details, NULL value means, it does not have value ( or you can say un-known).

NOT NULL is column-constraint. You would need to supply value always.

Best Example

Create Table Artist
(artist_id int not null,
dob date not null,
salary int);

So the artist table does not allow null values for artist_id and dob. You must enter values.

Here’s audio talk on SQL NOT NULL

The salary column is different, where it allows null values when you do not enter any amount.

Table Data of Artist

artist_id	DOB	Salary
1001	2000-01-19	10000
1002	2001-07-20	<null>
1003	2003-05-15	<null>

Summary

NOT NULL is a column constraint
Without values in the columns where NOT NULL defines, the SQL gives errors.
By default, all the columns accept NULL values

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Srini

Data Engineer with deep AI and Generative AI expertise, crafting high-performance data pipelines in PySpark, Databricks, and SQL. Skilled in Python, AWS, and Linux—building scalable, cloud-native solutions for smart applications.