Pass the Null Values for date fields and String fields and call the Tmp table insert method in Ax 2012

void clicked()
{
    Na_VendorTransTemp      na_VendorTransTemp1;
    super();

    FromDate.dateValue(dateNull());
    ToDate.dateValue(dateNull());
    VendorAccount.text("");
    VendorGroup.text("");

    delete_from na_VendorTransTemp1;
    Na_vendortransTmp_ds.refresh();
    Na_vendortransTmp_ds.research();
}

//Call the inserttable method in clicked method while using Tmp Table.

void clicked()
{
    Na_vendortransTmp.setTmpData(element.inserttable());
    Na_vendortransTmp_ds.executeQuery();
    Na_vendortransTmp_ds.reread();
    Na_vendortransTmp_ds.refresh();
    Na_vendortransTmp_ds.research();
}