对DBGrid的指定列的过滤

function FilterQryByDBG(aQry: TQuery; aDBGrid: TDBGrid; aFilterValue: string):
  string; //对DBGrid的指定列的过滤
var
  FieldNO: Integer;
  Condition: string;
begin
  with aQry do
  begin
    if not Active then Exit;
    FilterOptions := [foCaseInsensitive];
    Filtered := False;
    if (aFilterValue = '') then
      Exit;
    FieldNo := aDBGrid.SelectedIndex;
    if (aDBGrid.Fields[FieldNo].DataType = ftSmallint)
      or (aDBGrid.Fields[FieldNo].DataType = ftInteger)
      or (aDBGrid.Fields[FieldNo].DataType = ftfloat)
      or (aDBGrid.Fields[FieldNo].DataType = ftCurrency)
      or (aDBGrid.Fields[FieldNo].DataType = ftBCD) then
      Condition := aDBGrid.Columns[FieldNo].FieldName + '=' + aFilterValue;
    if (aDBGrid.Fields[FieldNo].DataType = ftstring) then
      Condition := aDBGrid.Columns[FieldNo].FieldName + '=''' + aFilterValue +
        '*' + '''';
    if (aDBGrid.Fields[FieldNo].DataType = ftdatetime) then
      Condition := aDBGrid.Columns[FieldNo].FieldName + '=''' + aFilterValue +
        '''';
    try
      Filter := Condition;
      Filtered := True;
    except
      Result := '请输入合适的条件!';
      Exit;
    end;
  end;
end;
/////
function LocateQryByDBG(aQry: TQuery; aDBGrid: TDBGrid; aLocateValue: string):
  string; //对DBGrid的指定列的定位
var
  i: Integer;
begin
  i := aDBGrid.SelectedIndex;
  if aLocateValue = '' then Exit;
  try
    if aDBGrid.Fields[i].DataType = FtInteger then
      aQry.Locate(aDBGrid.Columns[i].FieldName, StrToInt(aLocateValue),
        [loPartialKey])
    else
      aQry.Locate(aDBGrid.Columns[i].FieldName, aLocateValue, [loPartialKey]);
  except
    Result := '请输入合适的条件!';
    Exit;
  end;
end;