Timestamp Update with PHP

I am having trouble updating a timestamp field inside my database whenever I
use
the normal udpate xyz set x = now() etc etc I get must use case I use cast
and I get a ph error for the =...

ERROR: Unable to identify an operator '=' for types 'bpchar' and 'numeric'
You will have to retype this query using an explicit cast

Does anyone have an example of an update for a timestamp field using php.

I am really trying to use this with PHP and everytime I updated the record
because of a certain state I update the timestamp field.

Thanks..

Timothy Hitchens (Hitcho)
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