Testing for NULL Values

To evaluate columns for NULL values, use the following syntax.

column {= | <>} @NULL

The following returns TRUE if the column value is NULL, and thereby replicates the row. It returns FALSE for all other cases (including a column missing from the record).

WHERE (amount = @NULL)

The following returns TRUE only if the column is present in the record and is not NULL.

WHERE (amount = @PRESENT AND amount <> @NULL)

Note:

If a value in the trail contains more than 4000 bytes then the @NULL function will return TRUE.