Querying null values in a message in the MRM domain

If you want to compare an element to NULL, code the statement:

IF InputRoot.MRM.Elem2.Child1 IS NULL THEN
   DO:
    -- more ESQL --
END IF;

If nulls are permitted for this element, this statement tests whether the element exists in the input message, or whether it exists and contains the MRM-supplied null value. The behavior of this test depends on the physical format:

If you want to determine if the field is missing, rather than present but with null value, you can use the ESQL CARDINALITY function.

Related concepts
Message flows overview
ESQL overview
Message modeling
Custom wire format: NULL handling
XML wire format: NULL handling
TDS format: NULL handling
Related tasks
Setting null values in a message in the MRM domain
Designing a message flow
Defining message flow content
Managing ESQL files
Developing message models
Related reference
Compute node
Database node
Filter node
CAST function
ESQL reference
CARDINALITY function
IF statement