sybdataset.pas

sybase大全

unit SybDataSet;
interface
uses Windows, Db, Classes,
     SybBaseQuery,
     SybDatabase;

type
  PSybData = ^TSybData;
  TSybData = record
    Name  :array[0..29] of char;
    Id    :array[0..10] of char;
  end;

type
  // Bookmark information record to support TDataset bookmarks:
  PSybBookmarkInfo = ^TSybBookmarkInfo;
  TSybBookmarkInfo = record
    BookmarkData: Integer;
    BookmarkFlag: TBookmarkFlag;
  end;

  TSybDataSet = class(TDataSet)
  private
  public
    FQuery     :TSybBaseQuery;
    FTableName: string;
    FRecordPos: Integer;
    FRecordSize: Integer;
    FBufferSize: Integer;
    procedure SetTableName(const Value: string);
  protected
    { Mandatory overrides }
    // Record buffer methods:
    function AllocRecordBuffer: PChar; override;
    procedure FreeRecordBuffer(var Buffer: PChar); override;
    procedure InternalInitRecord(Buffer: PChar); override;
    function GetRecord(Buffer: PChar; GetMode: TGetMode;
      DoCheck: Boolean): TGetResult; override;
    function GetRecordSize: Word; override;
    procedure SetFieldData(Field: TField; Buffer: Pointer); override;
    // Bookmark methods:
    procedure GetBookmarkData(Buffer: PChar; Data: Pointer); override;
    function GetBookmarkFlag(Buffer: PChar): TBookmarkFlag; override;
    procedure InternalGotoBookmark(Bookmark: Pointer); override;
    procedure InternalSetToRecord(Buffer: PChar); override;
    procedure SetBookmarkFlag(Buffer: PChar; Value: TBookmarkFlag); override;
    procedure SetBookmarkData(Buffer: PChar; Data: Pointer); override;
    // Navigational methods:
    procedure InternalFirst; override;
    procedure InternalLast; override;
    // Editing methods:
    procedure InternalAddRecord(Buffer: Pointer; Append: Boolean); override;
    procedure InternalDelete; override;
    procedure InternalPost; override;
    // Misc methods:
    procedure InternalClose; override;
    procedure InternalHandleException; override;
    procedure InternalInitFieldDefs; override;
    procedure InternalOpen; override;
    function IsCursorOpen: Boolean; override;
    { Optional overrides }
    function GetRecordCount: Integer; override;
    function GetRecNo: Integer; override;
    procedure SetRecNo(Value: Integer); override;
  public
    constructor Create(AOwner: TComponent); override;
    destructor Destroy; override;
    function GetFieldData(Field: TField; Buffer: Pointer): Boolean; override;

  published
    property Active;
    property TableName: string read FTableName write SetTableName;
    property BufferCount;

    property BeforeOpen;
    property AfterOpen;
    property BeforeClose;
    property AfterClose;
    property BeforeInsert;
    property AfterInsert;
    property BeforeEdit;
    property AfterEdit;
    property BeforePost;
    property AfterPost;
    property BeforeCancel;
    property AfterCancel;
    property BeforeDelete;
    property AfterDelete;
    property BeforeScroll;
    property AfterScroll;
    property OnDeleteError;
    property OnEditError;
  end;

procedure Register;

implementation

uses BDE, DBTables, SysUtils, DBConsts, Forms, Controls, Dialogs;

procedure Register;
begin
  RegisterComponents('Sybase DBLIB', [TSybDataSet]);
end;
{ TSybDataSet }

function TSybDataSet.AllocRecordBuffer: PChar;
begin
  Result := AllocMem(FBufferSize);
end;

constructor TSybDataSet.Create(AOwner: TComponent);
begin
  inherited Create(AOwner);
  FRecordSize := SizeOf(TSybData);
  FBufferSize := FRecordSize + SizeOf(TSybBookmarkInfo);

  FQuery:=TSybBaseQuery.create(nil);
  FQuery.DbName:='db';
end;

destructor TSybDataSet.Destroy;
begin
  inherited Destroy;
end;

procedure TSybDataSet.FreeRecordBuffer(var Buffer: PChar);
begin
  FreeMem(Buffer);
end;

procedure TSybDataSet.GetBookmarkData(Buffer: PChar; Data: Pointer);
begin
  PInteger(Data)^ := PSybBookmarkInfo(Buffer + FRecordSize)^.BookmarkData;
end;

function TSybDataSet.GetBookmarkFlag(Buffer: PChar): TBookmarkFlag;
begin
  Result := PSybBookmarkInfo(Buffer + FRecordSize)^.BookmarkFlag;
end;

function TSybDataSet.GetFieldData(Field: TField; Buffer: Pointer): Boolean;
begin
  Result := True;
  case Field.Index of
    0:begin
        Move(PSybData(ActiveBuffer)^.Name, Buffer^, Field.DataSize);
      end;
    1:begin
        Move(PSybData(ActiveBuffer)^.Id, Buffer^, Field.DataSize);
      end
  end;
end;

function TSybDataSet.GetRecNo: Integer;
begin
  UpdateCursorPos;
  if (FRecordPos = -1) and (RecordCount > 0) then
    Result := 1
  else
    Result := FRecordPos + 1;
end;

function TSybDataSet.GetRecord(Buffer: PChar; GetMode: TGetMode;
  DoCheck: Boolean): TGetResult;
var
  IndexPos: Integer;
begin
  if FQuery.RowsAffected < 1 then
    Result := grEOF
  else
  begin
    Result := grOk;
    case GetMode of
      gmPrior:
        if FRecordPos <= 0 then
        begin
          Result := grBOF;
          FRecordPos := -1;
        end
        else
          Dec(FRecordPos);
      gmCurrent:
        if (FRecordPos < 0) or (FRecordPos >= RecordCount) then
           Result := grError;
      gmNext:
        if FRecordPos >= RecordCount-1 then
          Result := grEOF
        else
          Inc(FRecordPos);
    end;
    if Result = grOk then
    begin
      FQuery.GetRow(FRecordPos+1);

      strpcopy(PSybData(Buffer)^.Name,FQuery.Column(1));
      strpcopy(PSybData(Buffer)^.Id,FQuery.Column(2));

      with PSybBookmarkInfo(Buffer + FRecordSize)^ do
      begin
        BookmarkData := FRecordPos;
        BookmarkFlag := bfCurrent;
      end;
    end
    else if (Result = grError) and DoCheck then
      DatabaseError('No records');
  end;
end;

function TSybDataSet.GetRecordCount: Integer;
begin
  Result := FQuery.RowsAffected;
end;

function TSybDataSet.GetRecordSize: Word;
begin
  Result := FRecordSize;
end;

procedure TSybDataSet.InternalAddRecord(Buffer: Pointer; Append: Boolean);
begin
//
end;

procedure TSybDataSet.InternalClose;
begin
  if DefaultFields then
    DestroyFields;
  FRecordPos := -1;
end;

procedure TSybDataSet.InternalDelete;
begin
//
end;

procedure TSybDataSet.InternalFirst;
begin
  FRecordPos := -1;
end;

procedure TSybDataSet.InternalGotoBookmark(Bookmark: Pointer);
begin
  FRecordPos := Integer(Bookmark);
end;

procedure TSybDataSet.InternalHandleException;
begin
  // standard implementation for this method:
  Application.HandleException(Self);
end;

procedure TSybDataSet.InternalInitFieldDefs;
var i       :integer;
begin
  // create FieldDefs which map to each field in the data record
  FieldDefs.Clear;

//  TFieldDef.Create(FieldDefs, FQuery.heading(1), ftString, FQuery.collength(1), False, 1);
//  TFieldDef.Create(FieldDefs, FQuery.heading(2), ftString, 11, False, 2);

  for i:=1 to FQuery.Numcols do
  begin
    TFieldDef.Create(FieldDefs, FQuery.heading(i), ftString, FQuery.collength(i), False, i);
  end;
end;

procedure TSybDataSet.InternalInitRecord(Buffer: PChar);
begin
  FillChar(Buffer^, FBufferSize, 0);
end;

procedure TSybDataSet.InternalLast;
begin
  FRecordPos := FQuery.RowsAffected;
end;

procedure TSybDataSet.InternalOpen;
begin
//  if not FQuery.Active then
//  begin
//    MessageBox(GetActiveWindow,'Not connected to database','DB-Library error',mb_ok+mb_iconexclamation);
//    exit;
//  end;

  FQuery.Active:=True;
  FQuery.sql:='select name,id from develop..t_cursor';
  FQuery.sqlexec;
  while FQuery.nextrow = -1 do;
  try
    FRecordPos := -1;                   // initial record pos before BOF
    BookmarkSize := SizeOf(Integer);   // initialize bookmark size for VCL
    InternalInitFieldDefs;              // initialize FieldDef objects

    // Create TField components when no persistent fields have been created
    if DefaultFields then
      CreateFields;

    BindFields(True);                 // bind FieldDefs to actual data
  except
    raise;
  end;
end;

procedure TSybDataSet.InternalPost;
begin
//
end;

procedure TSybDataSet.InternalSetToRecord(Buffer: PChar);
begin
  FRecordPos := PSybBookmarkInfo(Buffer + FRecordSize)^.Bookmarkdata;
end;

function TSybDataSet.IsCursorOpen: Boolean;
begin
  Result:=FQuery.Active;
end;

procedure TSybDataSet.SetBookmarkData(Buffer: PChar; Data: Pointer);
begin
  PSybBookmarkInfo(Buffer + FRecordSize)^.BookmarkData := PInteger(Data)^;
end;

procedure TSybDataSet.SetBookmarkFlag(Buffer: PChar; Value: TBookmarkFlag);
begin
  PSybBookmarkInfo(Buffer + FRecordSize)^.BookmarkFlag := Value;
end;

procedure TSybDataSet.SetFieldData(Field: TField; Buffer: Pointer);
begin
  case Field.Index of
    0: Move(Buffer^, PSybData(ActiveBuffer)^.Name, Field.Size);
    1: Move(Buffer^, PSybData(ActiveBuffer)^.Id, Field.DataSize);
  end;
  DataEvent(deFieldChange, Longint(Field));
end;

procedure TSybDataSet.SetRecNo(Value: Integer);
begin
  if (Value >= 0) and (Value <= FQuery.RowsAffected-1) then
  begin
    FRecordPos := Value - 1;
    Resync([]);
  end;
end;

procedure TSybDataSet.SetTableName(const Value: string);
begin
  CheckInactive;
  FTableName := Value;
end;

end.