How to Handle Null or Not Present tags in xml file in BI Publisher?

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Hi all,

I have an issue where I'm stuck at making an XML condition for a check print. I used this SQL query for the same condition, and now I want it to be implemented in the RTF file.

SQL QUERY :

    CASE
        WHEN ACA.ATTRIBUTE1 IS NOT NULL THEN
            ACA.ATTRIBUTE1
        WHEN ACA.ATTRIBUTE1 IS NULL
             AND IPA.PAYEE_ALTERNATE_NAME IS NOT NULL THEN
            IPA.PAYEE_ALTERNATE_NAME
        ELSE
            IPA.PAYEE_NAME
    END                                       AS "PAYEE"

Can someone tell me how can I implement the same on the XML tag?

SrcDescriptiveFlexField/Attribute1   ;   SupplierorParty/AlternateName    ;    Payee/Name

The above-mentioned tags are the corresponding tags for the SQL I provided above.