To add lookup in form control

we are adding Form control lookup Vend accountNum and Vend name

public void lookup()
{
SysTableLookup sysTableLookup;
VendTable vendTable;
;
sysTableLookup = SysTableLookup::newParameters(tablenum(VendTable), this);

sysTableLookup.addLookupfield(fieldnum(vendTable, AccountNum),true);
sysTableLookup.addLookupfield(fieldnum(vendTable, Name),true);

sysTableLookup.performFormLookup();
//super();
}