Yogesh Chauhan's Blog

Check if any column has NULL values in Postgres

in Postgres on December 7, 2020

To check whether a value is or is not null, use the constructs

Syntax:


expression IS NULL
expression IS NOT NULL

or the equivalent, but nonstandard, constructs


expression ISNULL
expression NOTNULL

Do not write expression = NULL because NULL is not “equal to” NULL.

The null value represents an unknown value, and it is not known whether two unknown values are equal. This behavior conforms to the SQL standard.

Example:


SELECT product_name, unit_price 
FROM products 
WHERE supplier_id IS NULL;

//Output

0 rows

Meaning, all the rows have their supplier_id.


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