Compatible expressions in CASE conditions

I am attempting to update a database column with the maximum of the value currently stored in the column and the contents of a host variable. For example: EXEC SQL UPDATE DB_TABLE SET DB_COLUMN = CASE WHERE DB_COLUMN > :hostVar THEN DB_COLUMN ELSE :hostVar END; When I compile and execute the above statement, I get a sqlca.sqlcode of -800 (Corresponding types must be compatible in CASE expression). I have run some tests and found that UPDATE will only succeed if the contents of the THEN and ELSE in the CASE are identical. For instance: CASE WHERE DB_COLUMN > :hostVar THEN DB_COLUMN ELSE DB_COLUNN2 END or CASE WHERE DB_COLUMN > :hostVar THEN :hostVar ELSE :hostVar2 END It seems that host variables and column names are not considered compatible expressions. This is contrary to the information in the Informix SQL Syntax Guide. Does anyone see anything wrong with my initial SQL or have another suggestion for how to accomplish this task without doing a SELECT before the UPDATE? Thanks, Gregory Scarborough