If what you have posted is the entire sql, then you will get the error because you’re not referencing a table. Normally a prompt is a part of a condition, like:
table.year_number = @Prompt('Enter or Select an Invoice Year: ','A','ATT Long Distance Detail\Invoice Year',Mono,Free)
If you don’t want to use it as a condition, but still want the prompt, then ignore the parse error and try using the object within a report, using at least one “real” object that does reference a table.