Dynamic SQL. Is it possible?

[Peter Hamilton-Scott]

I need to write an update SP that will take three (optionally nullable) parameters. The concept of nullable means I would not need to update the column affected by it. So, a call like CALL UPDATER(1, null, 3) would require an update to say, col1 and col3, but no change to col2. Using the concept of dynamic SQL that I've worked with in DB2 I could, based on the parameters I'm given, build a varchar string containing the runtime SQL to be executed. Something on the lines of:

UPDATE TABLEX SET COL1=PAR1, COL3=PAR3...
...or...
UPDATE TABLEX SET COL2=PAR2, COL3=PAR3...

If I create this varchar string then is it possible to run it as SQL?

I don't know if that is possible, but any advice will be appreciated.

Thanks.