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2977:Listing the field structures of a table.

KEYWORDS: fields, field types AREA: Application Interop

Q:  How can I list the field structures of a table?

A:  This project demonstrates listing the field structure from
a given table, using the Fields and IndexDefs arrays, and
displaying them in a listbox.

There is a demo (dbbrowsr.dpr) approaches this task
differently.  You may want to compare the two versions of this
code.

Note:  This code works with 16 bit only.

procedure TForm1.Button1Click(Sender: TObject); const
MyFielddefs: array[ftUnknown..ftGraphic] of string [8] =
  ('Unknown', 'String', 'Smallint', 'Integer', 'Word',
  'Boolean', 'Float', 'Currency', 'BCD', 'Date',
  'Time', 'DateTime', 'Bytes', 'VarBytes', 'Blob',
  'Memo', 'Graphic');

var
  i, Indx: integer;
  Definition: string;
begin
  for i := 0 to Table1.FieldCount - 1 do begin
    Definition := Table1.Fields[i].DisplayLabel;
    Definition := Definition + ' ' +
      MyFieldDefs[Table1.Fields[i].DataType];
    Table1.IndexDefs.Update;
    if Table1.Fields[i].IsIndexField then begin
      Indx := Table1.IndexDefs.Indexof(Table1.Fields[i].Name);
      if Indx > -1 then
        if ixPrimary in Table1.IndexDefs[Indx].Options then
          Definition := Definition + ' (Primary)';
    end;
    Listbox1.Items.Add(Definition);
  end;
end;

The version above does not work with the 32 bit version as
there are more field types that must now be taken into
account.  Here is a version that works with the 32 bit version:

procedure TForm1.Button1Click(Sender: TObject);
const
  MyFielddefs: array[ftUnknown..ftTypedBinary] of string [11] =
    ('Unknown', 'String', 'Smallint', 'Integer',
    'Word', 'Boolean', 'Float', 'Currency', 'BCD',
    'Date', 'Time', 'DateTime', 'Bytes', 'VarBytes',
    'AutoInc', 'Blob', 'Memo', 'Graphic', 'FmtMemo',
    'ParadoxOle', 'DBaseOle', 'TypedBinary');

var
  i, Indx: integer;
  Definition: string;
begin
  for i := 0 to Table1.FieldCount - 1 do begin
    Definition := Table1.Fields[i].DisplayLabel;
    Definition := Definition + ' ' +
      MyFieldDefs[Table1.Fields[i].DataType];
    Table1.IndexDefs.Update;
    if Table1.Fields[i].IsIndexField then begin
      Indx := Table1.IndexDefs.Indexof(Table1.Fields[i].Name);
      if Indx > -1 then
        if ixPrimary in Table1.IndexDefs[Indx].Options then
          Definition := Definition + ' (Primary)';
    end;
    Listbox1.Items.Add(Definition);
  end;
end;




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