TParam.DataType Property

Indicates the type of field whose value the parameter represents.

Pascal

property DataType: TFieldType;

C++

__property TFieldType DataType;

Description

DataType is set automatically when a value is assigned to the parameter. Do not set DataType for bound fields, as that may cause the assigned value to be misinterpreted.

Read DataType to discover the type of data that was assigned to the parameter. Each possible value of DataType corresponds to a type of database field.

C++ Examples:

Copy Code

/*
This example requires a TClientDataSet and a button on a form.
Put swSystem in the uses clause for gsAppPath.
*/
void __fastcall TForm1::Button1Click(TObject *Sender)
{
for (int I = 0; I < CDS->Params->Count; I++)
{
  if (CDS->Params->Items[I]->IsNull &&
      CDS->Params->Items[I]->DataType == ftInteger)
    CDS->Params->Items[I]->AsInteger = -1;
}}

#include <swSystem.hpp>

void __fastcall TForm1::FormCreate(TObject *Sender)
{
  CDS->LoadFromFile(gsAppPath + "../CDS.XML");
  CDS->Params->CreateParam(ftInteger, "StateParam", ptInput);
  CDS->Params->CreateParam(ftInteger, "MyParam", ptInput);
}

Delphi Examples:

Copy Code

{
This example fills in the parameters of a client dataset
from the entries of a list box.
} 
procedure TForm1.Button4Click(Sender: TObject);
var
  I: Integer;
  ListItem: string;
begin
  { Call FetchParams to ensure parameters reflect server metadata }
  ClientDataSet1.FetchParams;
  with ClientDataSet1.Params do
  begin
    for I := 0 to Count - 1 do
    begin
      ListItem := ListBox1.Items[I];
      case Items[I].DataType of
        ftString:
          Items[I].AsString := ListItem;
        ftSmallInt:
          Items[I].AsSmallInt := StrToIntDef(ListItem, 0);
        ftInteger:
          Items[I].AsInteger := StrToIntDef(ListItem, 0);
        ftWord:
          Items[I].AsWord := StrToIntDef(ListItem, 0);
        ftBoolean:
          begin
            if ListItem = 'True' then
              Items[I].AsBoolean := True
            else
              Items[I].AsBoolean := False;
          end;
        ftFloat:
          Items[I].AsFloat := StrToFloat(ListItem);
        ftCurrency:
          Items[I].AsCurrency := StrToFloat(ListItem);
        ftBCD:
          Items[I].AsBCD := StrToCurr(ListItem);
        ftDate:
          Items[I].AsDate := StrToDate(ListItem);
        ftTime:
          Items[I].AsTime := StrToTime(ListItem);
        ftDateTime:
          Items[I].AsDateTime := StrToDateTime(ListItem);
      end;
    end;
  end;
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
  ListBox1.Items.Add('Here is a string');
  ListBox1.Items.Add('4');
  ListBox1.Items.Add('3456789');
  ListBox1.Items.Add('34');
  ListBox1.Items.Add('0');
  ListBox1.Items.Add('12.56');
  ListBox1.Items.Add('4.23');
  ListBox1.Items.Add('99.5');
  ListBox1.Items.Add('4/12/53');
  ListBox1.Items.Add('7:45:00');
  ListBox1.Items.Add('4/12/53 7:45:00');

end;

Copy Code

{
This example requires a TClientDataSet and a button on a form.
Put swSystem in the uses clause for gsAppPath.
}
procedure TForm1.Button1Click(Sender: TObject);
var
  I : Integer;
begin
{ Assign -1 to any integer parameter which does not have a value. }
for I := 0 to CDS.Params.Count - 1 do
  if (CDS.Params.Items[I].IsNull) and
     (CDS.Params.Items[I].DataType = ftInteger) then
    { Items is the default property, so you can omit its name }
    CDS.Params[I].AsInteger := -1;
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
  CDS.LoadFromFile(gsAppPath + 'CDS.XML');
  CDS.Params.CreateParam(ftInteger, 'StateParam', ptInput);
  CDS.Params.CreateParam(ftInteger, 'MyParam', ptInput);
end;