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unit BDEClientDataSet;

interface

uses Windows, SysUtils, Variants, Classes, DB, DBCommon, Midas,
SqlTimSt, DBClient, DBLocal, Provider, DBTables;

type
{ TBDEQuery }

TBDEQuery = class(TQuery)
private
FKeyFields: string;
protected
function PSGetDefaultOrder: TIndexDef; override;
end;

{ TBDEClientDataSet }
TBDEClientDataSet = class(TCustomCachedDataSet)
private
    FCommandText: string;
    FCurrentCommand: string;
    FDataSet: TBDEQuery;
    FDatabase: TDataBase;
    FLocalParams: TParams;
    FStreamedActive: Boolean;
    procedure CheckMasterSourceActive(MasterSource: TDataSource);
    procedure SetDetailsActive(Value: Boolean);
    function GetConnection: TDataBase;
    function GetDataSet: TDataSet;
    function GetMasterSource: TDataSource;
    function GetMasterFields: string;
    procedure SetConnection(Value: TDataBase);
    procedure SetDataSource(Value: TDataSource);
    procedure SetLocalParams;
    procedure SetMasterFields(const Value: string);
    procedure SetParamsFromSQL(const Value: string);
    procedure SetSQL(const Value: string);
protected
    function GetCommandText: String; override;
    procedure Loaded; override;
    procedure Notification(AComponent: TComponent; Operation: TOperation); override;
    procedure SetActive(Value: Boolean); override;
    procedure SetCommandText(Value: string); override;
public
    constructor Create(AOwner: TComponent); override;
    destructor Destroy; override;
    procedure CloneCursor(Source: TCustomClientDataSet; Reset: Boolean;
      KeepSettings: Boolean = False); override;
    procedure GetFieldNames(List: TStrings); override;
    function GetQuoteChar: String;
    property DataSet: TDataSet read GetDataSet;
published
    property Active;
    property CommandText: string read GetCommandText write SetCommandText;
    property DBConnection: TDataBase read GetConnection write SetConnection;
    property MasterFields read GetMasterFields write SetMasterFields;
    property MasterSource: TDataSource read GetMasterSource write SetDataSource;
end;

procedure Register;

implementation

uses BDEConst, MidConst;

type

{ TBDECDSParams }

TBDECDSParams = class(TParams)
private
    FFieldName: TStrings;
protected
    procedure ParseSelect(SQL: string);
public
    constructor Create(Owner: TPersistent);
    Destructor Destroy; override;
end;

constructor TBDECDSParams.Create(Owner: TPersistent);
begin
inherited;
FFieldName := TStringList.Create;
end;

destructor TBDECDSParams.Destroy;
begin
FreeAndNil(FFieldName);
inherited;
end;

procedure TBDECDSParams.ParseSelect(SQL: string);
const
SSelect = select;
var
FWhereFound: Boolean;
Start: PChar;
FName, Value: string;
SQLToken, CurSection, LastToken: TSQLToken;
Params: Integer;
begin
if Pos( + SSelect + , LowerCase(string(PChar(SQL)+8))) > 1 then Exit; // cant parse sub queries
Start := PChar(ParseSQL(PChar(SQL), True));
CurSection := stUnknown;
LastToken := stUnknown;
FWhereFound := False;
Params := 0;
repeat
    repeat
      SQLToken := NextSQLToken(Start, FName, CurSection);
      if SQLToken in [stWhere] then
      begin
        FWhereFound := True;
        LastToken := stWhere;
      end else if SQLToken in [stTableName] then
      begin
        { Check for owner qualified table name }
        if Start^ = . then
          NextSQLToken(Start, FName, CurSection);
      end else
      if (SQLToken = stValue) and (LastToken = stWhere) then
        SQLToken := stFieldName;
      if SQLToken in SQLSections then CurSection := SQLToken;
    until SQLToken in [stFieldName, stEnd];
    if FWhereFound and (SQLToken in [stFieldName]) then
      repeat
        SQLToken := NextSQLToken(Start, Value, CurSection);
          if SQLToken in SQLSections then CurSection := SQLToken;
      until SQLToken in [stEnd,stValue,stIsNull,stIsNotNull,stFieldName];
    if Value=? then
    begin
      FFieldName.Add(FName);
      Inc(Params);
    end;
until (Params = Count) or (SQLToken in [stEnd]);
end;

{ TBDEQuery }

function TBDEQuery.PSGetDefaultOrder: TIndexDef;
begin
    if FKeyFields = then
      Result := inherited PSGetDefaultOrder
    else
    begin // detail table default order
      Result := TIndexDef.Create(nil);
      Result.Options := [ixUnique];      // keyfield is unique
      Result.Name := StringReplace(FKeyFields, ;, _, [rfReplaceAll]);
      Result.Fields := FKeyFields;
    end;
end;

{ TBDEClientDataSet }

constructor TBDEClientDataSet.Create(AOwner: TComponent);
begin
inherited Create(AOwner);
FDataSet := TBDEQuery.Create(nil);
FDataSet.Name := Self.Name + DataSet1;
Provider.DataSet := FDataSet;
SqlDBType := typeBDE;
FLocalParams := TParams.Create;
end;

destructor TBDEClientDataSet.Destroy;
begin
FreeAndNil(FLocalParams);
FDataSet.Close;
FreeAndNil(FDataSet);
inherited Destroy;
end;

procedure TBDEClientDataSet.GetFieldNames(List: TStrings);
var
Opened: Boolean;
begin
Opened := (Active = False);
try
    if Opened then
      Open;
    inherited GetFieldNames(List);
finally
    if Opened then Close;
end;
end;

function TBDEClientDataSet.GetCommandText: string;
begin
Result := FCommandText;
end;

function TBDEClientDataSet.GetDataSet: TDataSet;
begin
Result := FDataSet as TDataSet;
end;

procedure TBDEClientDataSet.CheckMasterSourceActive(MasterSource: TDataSource);
begin
if Assigned(MasterSource) and Assigned(MasterSource.DataSet) then
if not MasterSource.DataSet.Active then
DatabaseError(SMasterNotOpen);
end;

procedure TBDEClientDataSet.SetParamsFromSQL(const Value: string);
var
DataSet: TQuery;
TableName, TempQuery, Q: string;
List: TBDECDSParams;
I: Integer;
Field: TField;
begin
TableName := GetTableNameFromSQL(Value);
if TableName <> then
begin
    TempQuery := Value;
    List := TBDECDSParams.Create(Self);
    try
      List.ParseSelect(TempQuery);
        List.AssignValues(Params);
      for I := 0 to List.Count - 1 do
        List[I].ParamType := ptInput;
      DataSet := TQuery.Create(nil);
      try
        DataSet.DatabaseName := FDataSet.DatabaseName;
        Q := GetQuoteChar;
        DataSet.SQL.Add(select * from + Q + TableName + Q + where 0 = 1); { do not localize }
        try
          DataSet.Open;
          for I := 0 to List.Count - 1 do
          begin
            if List.FFieldName.Count > I then
            begin
              try
                Field := DataSet.FieldByName(List.FFieldName[I]);
              except
                Field := nil;
              end;
            end else
              Field := nil;
            if Assigned(Field) then
            begin
              if Field.DataType <> ftString then
                List[I].DataType := Field.DataType
              else if TStringField(Field).FixedChar then
                List[I].DataType := ftFixedChar
              else
                List[I].DataType := ftString;
            end;
          end;
        except
          // ignore all exceptions
        end;
      finally
        DataSet.Free;
      end;
    finally
      if List.Count > 0 then
        Params.Assign(List);
      List.Free;
    end;
end;
end;

procedure TBDEClientDataSet.SetSQL(const Value: string);
begin
if Assigned(Provider.DataSet) then
begin
    TQuery(Provider.DataSet).SQL.Clear;
    if Value <> then
      TQuery(Provider.DataSet).SQL.Add(Value);
    inherited SetCommandText(Value);
end else
    DataBaseError(SNoDataProvider);
end;

procedure TBDEClientDataSet.Loaded;
begin
inherited Loaded;
if FStreamedActive then
begin
SetActive(True);
FStreamedActive := False;
end;
end;

function TBDEClientDataSet.GetMasterFields: string;
begin
Result := inherited MasterFields;
end;

procedure TBDEClientDataSet.SetMasterFields(const Value: string);
begin
inherited MasterFields := Value;
if Value <> then
IndexFieldNames := Value;
FDataSet.FKeyFields := ;
end;

procedure TBDEClientDataSet.SetCommandText(Value: String);
begin
inherited SetCommandText(Value);
FCommandText := Value;
if not (csLoading in ComponentState) then
begin
    FDataSet.FKeyFields := ;
    IndexFieldNames := ;
    MasterFields := ;
    IndexName := ;
    IndexDefs.Clear;
    Params.Clear;
    if (csDesigning in ComponentState) and (Value <> ) then
      SetParamsFromSQL(Value);
end;
end;

function TBDEClientDataSet.GetConnection: TDatabase;
begin
Result := FDataBase;
end;

procedure TBDEClientDataSet.SetConnection(Value: TDataBase);
begin
if Value = FDatabase then exit;
CheckInactive;
if Assigned(Value) then
begin
    if not (csLoading in ComponentState) and (Value.DatabaseName = ) then
      DatabaseError(SDatabaseNameMissing);
    FDataSet.DatabaseName := Value.DatabaseName;
end else
    FDataSet.DataBaseName := ;
FDataBase := Value;
end;

function TBDEClientDataSet.GetQuoteChar: String;
begin
Result := ;
if Assigned(FDataSet) then
Result := FDataSet.PSGetQuoteChar;
end;

procedure TBDEClientDataSet.CloneCursor(Source: TCustomClientDataSet; Reset: Boolean;
KeepSettings: Boolean = False);
begin
if not (Source is TBDEClientDataSet) then
DatabaseError(SInvalidClone);
Provider.DataSet := TBDEClientDataSet(Source).Provider.DataSet;
DBConnection := TBDEClientDataSet(Source).DBConnection;
CommandText := TBDEClientDataSet(Source).CommandText;
inherited CloneCursor(Source, Reset, KeepSettings);
end;

procedure TBDEClientDataSet.Notification(AComponent: TComponent; Operation: TOperation);
begin
inherited Notification(AComponent, Operation);
if Operation = opRemove then
    if AComponent = FDatabase then
    begin
      FDataBase := nil;
      SetActive(False);
    end;
end;

procedure TBDEClientDataSet.SetLocalParams;

procedure CreateParamsFromMasterFields(Create: Boolean);
var
    I: Integer;
    List: TStrings;
begin
    List := TStringList.Create;
    try
      if Create then
        FLocalParams.Clear;
      FDataSet.FKeyFields := MasterFields;
      List.CommaText := MasterFields;
      for I := 0 to List.Count -1 do
      begin
        if Create then
          FLocalParams.CreateParam( ftUnknown, MasterSource.DataSet.FieldByName(List[I]).FieldName,
                     ptInput);
        FLocalParams[I].AssignField(MasterSource.DataSet.FieldByName(List[I]));
      end;
    finally
      List.Free;
    end;
end;

begin
if (MasterFields <> ) and Assigned(MasterSource) and Assigned(MasterSource.DataSet) then
begin
CreateParamsFromMasterFields(True);
FCurrentCommand := AddParamSQLForDetail(FLocalParams, CommandText, True, GetQuoteChar);
end;
end;

procedure TBDEClientDataSet.SetDataSource(Value: TDataSource);
begin
inherited MasterSource := Value;
if Assigned(Value) then
begin
if PacketRecords = -1 then PacketRecords := 0;
end else
begin
if PacketRecords = 0 then PacketRecords := -1;
end;
end;

function TBDEClientDataSet.GetMasterSource: TDataSource;
begin
Result := inherited MasterSource;
end;

procedure TBDEClientDataSet.SetDetailsActive(Value: Boolean);
var
DetailList: TList;
I: Integer;
begin
DetailList := TList.Create;
try
    GetDetailDataSets(DetailList);
    for I := 0 to DetailList.Count -1 do
    if TDataSet(DetailList[I]) is TBDEClientDataSet then
      TBDEClientDataSet(TDataSet(DetailList[I])).Active := Value;
finally
    DetailList.Free;
end;
end;

procedure TBDEClientDataSet.SetActive(Value: Boolean);
begin
if Value then
begin
    if csLoading in ComponentState then
    begin
      FStreamedActive := True;
      exit;
    end;
    if MasterFields <> then
    begin
      if not (csLoading in ComponentState) then
        CheckMasterSourceActive(MasterSource);
      SetLocalParams;
      SetSQL(FCurrentCommand);
      Params := FLocalParams;
      FetchParams;
    end else
    begin
      SetSQL(FCommandText);
      if Params.Count > 0 then
      begin
        FDataSet.Params := Params;
        FetchParams;
      end;
    end;
end;
if Value and (FDataSet.ObjectView <> ObjectView) then
    FDataSet.ObjectView := ObjectView;
inherited SetActive(Value);
SetDetailsActive(Value);
end;

procedure Register;
begin
RegisterComponents(BDE, [TBDEClientDataSet]);
end;

end.

//以上经DBLocalB.pas改装而成,可存为任意文件名,当然扩展名是PAS
//然后安装此控件即可