function GetVal(v: variant): string;
begin
  result := VarToStr(v);
  
  case VarType(v) of
    varEmpty: result := 'null';
    varString: if (v = '') or (v = '0') then result := 'null' else result := QuotedStr(VarToStr(v));
    varInteger, varSmallInt, varSingle, varDouble, varCurrency, varShortInt, varWord: if v = 0 then result := 'null';
  else
    if VarIsNull(v) then result := 'null';

  end;
end;

// Show the type of a variant
procedure TForm1.ShowBasicVariantType(varVar: Variant);
var
 typeString : string;
 basicType : Integer;
begin
 // Get the Variant basic type :
 // this means excluding array or indirection modifiers
 basicType := VarType(varVar) and VarTypeMask;
 // Set a string to match the type
 case basicType of
 varEmpty : typeString := 'varEmpty';
 varNull : typeString := 'varNull';
 varSmallInt : typeString := 'varSmallInt';
 varInteger : typeString := 'varInteger';
 varSingle : typeString := 'varSingle';
 varDouble : typeString := 'varDouble';
 varCurrency : typeString := 'varCurrency';
 varDate : typeString := 'varDate';
 varOleStr : typeString := 'varOleStr';
 varDispatch : typeString := 'varDispatch';
 varError : typeString := 'varError';
 varBoolean : typeString := 'varBoolean';
 varVariant : typeString := 'varVariant';
 varUnknown : typeString := 'varUnknown';
 varByte : typeString := 'varByte';
 varWord : typeString := 'varWord';
 varLongWord : typeString := 'varLongWord';
 varInt64 : typeString := 'varInt64';
 varStrArg : typeString := 'varStrArg';
 varString : typeString := 'varString';
 varAny : typeString := 'varAny';
 varTypeMask : typeString := 'varTypeMask';
 end;
 // Show the Variant type
 ShowMessage('Variant type is '+typeString);
end;