Use the following syntax to declare the datatype for a parameter in a stored procedure:
create procedure [owner.]procedure_name [;number] [[(]@parameter_name datatype [= default] [output] [,@parameter_name datatype [= default] [output]]...[)]] [with recompile] as SQL_statements
For example:
create procedure auname_sp @auname varchar(40) as select au_lname, title, au_ord from authors, titles, titleauthor where @auname = au_lname and authors.au_id = titleauthor.au_id and titles.title_id = titleauthor.title_id