Handling Null Values
To check at mapping runtime whether a database field is null, use the is-null and is-not-null MapForce library functions. To see from MapForce if a table has null fields, query it using the Database Browser (see Browsing and Querying Databases).
To set a database field to null, use the set-null function.
To replace null database values with a string, use the substitute-null function. A sample mapping that illustrates this is DB_ApplicationList.mfd available in the <Documents>\Altova\MapForce2023\MapForceExamples\ folder.
For information about handling NULL value comparisons in mappings which update databases, see Handling Nulls in Database Table Actions.
For information about handling nulls when mapping database to or from XML documents, see Nil Values / Nillable.