Replaces null (returned as a blank) with character data in the results of a query. If the first expression specified is null, then NVL returns second expression specified. If first expression specified is not null, then NVL returns the value of the first expression.



The following restrictions apply when you use the NVL function in the SELECT command:

  • The replacement value (second expression) must be specified as character data.

  • The function does not support data conversions.


This example replaces NULL in the output for singalling_component with the text "No component."

select nvl(signalling_component, 'No component') from incident;