CASE statement with NULL value

I'm struggling to understand how to check for a null value in a progress case statement. I want to see if a column exists and use that, if not use the fallback column. For example, William in first name would be over written by Bill in fn.special-char.

I've got the following query:

SELECT
"PUB"."NAME"."LAST-NAME" as LastName,
CASE fn."SPECIAL-CHAR"
WHEN is null THEN "PUB"."NAME"."FIRST-NAME"
ELSE fn."SPECIAL-CHAR"
END as FirstName

FROM "PUB"."NAME"
LEFT OUTER JOIN "PUB"."DAT-DATA" fn on "PUB"."NAME"."NAME-ID" = fn."DAT-SRC-ID" and 11 = fn."FLD-FIELD-ID"


When I run the query I get:

ORBC Progress OpenEdge Wire Protocol driver][OPENEDGE]Syntax error SQL statement at or about "is null then "PUB"."NAME"."FIRST-" (10713)
​

If I do a select * I see everything. It just doesn't like the null part. I can also change the when is null to when 'bob' and it works.

Is there something different I need to do to use a null value in a progress db query?

Continue reading...