# duration_null¶

## Description¶

Returns a null value of type duration. This is important, because some functions, like case(), return more convenient outputs if all their arguments are of the same type.

duration

## Domain¶

This is a scalar function (calculates a single output value for a single input row.)

## Usage¶

duration_null( )


## Examples¶

make_col positive_or_null:case(x > 0, x, true, duration_null())


Create a column ‘positive_or_null’ which is either a positive duration, or the null duration.