$stmt – A prepared statement resource that was returned by the sasql_prepare function.
$param_number – The parameter number. This should be a number between 0 and (sasql_stmt_param_count($stmt) - 1).
$var – A PHP variable. Only references to PHP variables are allowed.
$type – Type of the variable. This can be one of: s for string, i for integer, d for double, b for blobs.
$is_null – Whether the value of the variable is NULL or not.
$direction – Can be SASQL_D_INPUT, SASQL_D_OUTPUT, or SASQL_INPUT_OUTPUT.