SQL Server supportsISNULL function that replacesNULL with a specified replacement value:

ISNULL(expression, replacement)

If theexpression is NULL, then theISNULL function returns thereplacement. Otherwise, it returns the result of theexpression.

PostgreSQL does not have theISNULL function. However, you can use theCOALESCE function which provides similar functionality.

Note that theCOALESCE function returns the first non-null argument, so the following syntax has a similar effect as theISNULL function above:

COALESCE(expression,replacement)

For theCOALESCE example, check out theCOALESCE function tutorial.

In addition toCOALESCE function, you can use theCASE expression:

SELECT    CASE WHEN expression IS NULL            THEN replacement            ELSE expression    END AS column_alias;

Check out theCASE expression tutorial for more information.

Last updated onFebruary 1, 2024