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最后，讓我們檢查最后一個組件TfrxIBXQuery. 它繼承自TfrxCustomQuery基本類，其中已經(jīng)定義了必要的屬性。我們只需要定義Database屬性和覆蓋SetMaster方法。其他方法實現(xiàn)與TfrxIBXTable組件類似。

  TfrxIBXQuery = class(TfrxCustomQuery)
  private
    FDatabase: TfrxIBXDatabase;
    FQuery: TIBQuery;
    procedure SetDatabase(const Value: TfrxIBXDatabase);
  protected
    procedure Notification(AComponent: TComponent; Operation: TOperation); override;
    procedure SetMaster(const Value: TDataSource); override;
    procedure SetSQL(Value: TStrings); override;
    function GetSQL: TStrings; override;
  public
    constructor Create(AOwner: TComponent); override;
    constructor DesignCreate(AOwner: TComponent; Flags: Word); override;
    class function GetDescription: String; override;
    procedure BeforeStartReport; override;
    procedure UpdateParams; override;
    property Query: TIBQuery read FQuery;
  published
    property Database: TfrxIBXDatabase read FDatabase write SetDatabase;
  end;

constructor TfrxIBXQuery.Create(AOwner: TComponent);
begin
  { create component – query }
  FQuery := TIBQuery.Create(nil);
  { assign link to it to DataSet property from basic class – do not forget this line! }
  Dataset := FQuery;
  { assign link to connection to DB by default }
  SetDatabase(nil);
  { after that basic constructor may be called in }
  inherited;
end;

constructor TfrxIBXQuery.DesignCreate(AOwner: TComponent; Flags: Word);
var
  i: Integer;
  l: TList;
begin
  inherited;
  l := Report.AllObjects;
  for i := 0 to l.Count - 1 do
    if TObject(l[i]) is TfrxIBXDatabase then
    begin
      SetDatabase(TfrxIBXDatabase(l[i]));
      break;
    end;
end;

class function TfrxIBXQuery.GetDescription: String;
begin
  Result := 'IBX Query';
end;

procedure TfrxIBXQuery.Notification(AComponent: TComponent; Operation: TOperation);
begin
  inherited;
  if (Operation = opRemove) and (AComponent = FDatabase) then
    SetDatabase(nil);
end;

procedure TfrxIBXQuery.SetDatabase(const Value: TfrxIBXDatabase);
begin
  FDatabase := Value;
  if Value <> nil then
    FQuery.Database := Value.Database
  else if IBXComponents <> nil then
    FQuery.Database := IBXComponents.DefaultDatabase
  else
    FQuery.Database := nil;
  DBConnected := FQuery.Database <> nil;
end;

procedure TfrxIBXQuery.SetMaster(const Value: TDataSource);
begin
  FQuery.DataSource := Value;
end;

function TfrxIBXQuery.GetSQL: TStrings;
begin
  Result := FQuery.SQL;
end;

procedure TfrxIBXQuery.SetSQL(Value: TStrings);
begin
  FQuery.SQL := Value;
end;

procedure TfrxIBXQuery.UpdateParams;
begin
  { in this method it is sufficient to assign values from Params into FQuery.Params }
  { this is performed via standard procedure }
  frxParamsToTParams(Self, FQuery.Params);
end;

procedure TfrxIBXQuery.BeforeStartReport;
begin
  SetDatabase(FDatabase);
end;

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