Greetings Mark
>>
>
>Try no quotes and no periods arount NULL.

OK, just tried

>>SQLPREPARE(gnhandle,"update vizkeys set date_used=NULL where date_used<>'.NULL.' ","real")

and it complained about string conversion

so I tried

>>SQLPREPARE(gnhandle,"update vizkeys set date_used=NULL where date_used<>.NULL. ","real")

and it complained about a syntax problem near NULL

then I tried

>>SQLPREPARE(gnhandle,"update vizkeys set date_used=NULL where date_used<>NULL ","real")

and it didn't protest. But neither did it replace a single value.

Jeez!