myldbvariant.pas

一个本地database引擎,支持中文T_Sql查询,兼容DELPHI标准数据库控件

//------------------------------------------------------------------------------
// SetNull
//------------------------------------------------------------------------------
procedure TMYLDBVariant.SetNull(DataType: TMYLDBBaseFieldType);
begin
  FIsNull := True;
end;//SetNull


//------------------------------------------------------------------------------
// Free Buffer
//------------------------------------------------------------------------------
procedure TMYLDBVariant.Clear(DataType: TMYLDBBaseFieldType);
begin
  if ((FPData <> nil) and (not FIsDataLinked)) then
      MemoryManager.FreeAndNillMem(FPData);
  FPData := nil;
  FDataType := DataType;
  FDataSize := 0;
  FIsDataLinked := false;
  FIsNull := True;
end;//Clear


//------------------------------------------------------------------------------
// Set Data Type
//------------------------------------------------------------------------------
procedure TMYLDBVariant.SetDataType(DataType: TMYLDBBaseFieldType);
begin
  if not IsNull then
    try
      Cast(DataType);
    except
      Clear(DataType);
    end
  else
   if (FPData <> nil) then
    Clear(DataType)
   else
    FDataType := DataType;
end;//SetDataType


//------------------------------------------------------------------------------
// CastResultToType
//------------------------------------------------------------------------------
procedure TMYLDBVariant.CastResultToType(NewDataType: TMYLDBBaseFieldType; out Result);
var
  p: Pointer;
  TmpSize: Integer;
begin
  p := CastToNewBuffer(FPData, FDataSize, FDataType, NewDataType, TmpSize);
    case NewDataType of
      bftChar,
      bftVarChar:
        begin
          SetLength(String(Result), TmpSize-1);
          if (PChar(Result) <> nil) then
            Move(PChar(p)^, PChar(Result)^, TmpSize);
        end;
      bftWideChar, bftWideVarChar:
        begin
          SetLength(WideString(Result), (TmpSize) div 2 - 1);
          if (PWideChar(Result) <> nil) then
            Move(PWideChar(p)^, PWideChar(Result)^, TmpSize);
        end;
      else
        Move(p^, Result, TmpSize);
    end;
  MemoryManager.FreeAndNillMem(p);
end;//CastResultToType


//------------------------------------------------------------------------------
// Cast value to empty FPData
//------------------------------------------------------------------------------
procedure TMYLDBVariant.CastAndSetData(const Value; ValueType: TMYLDBBaseFieldType);
var p: Pointer;
begin
  if ((FPData <> nil) and (not FIsDataLinked)) then
    MemoryManager.FreeAndNillMem(FPData);
  if (ValueType in [bftChar, bftVarChar, bftWideChar, bftWideVarchar]) then
    p := Pointer(Value)
  else
    p := @Value;
  FPData := CastToNewBuffer(p, -1, ValueType, FDataType, FDataSize);
end;//CastAndSetData


//------------------------------------------------------------------------------
// raise EMYLDBException if FPData = nil
//------------------------------------------------------------------------------
procedure TMYLDBVariant.CheckDataForNull;
begin
 if IsNull then
   raise EMYLDBException.Create(30016, ErrorGValueIsNull);
end;//CheckDataForNull


//------------------------------------------------------------------------------
// Assign data from source (or make link to Source.Data)
//------------------------------------------------------------------------------
procedure TMYLDBVariant.Assign(Source: TMYLDBVariant; CopyDataFlag: boolean = true);
begin
  Clear;
  FDataType := Source.FDataType;
  FDataSize := Source.FDataSize;
  FIsDataLinked := not CopyDataFlag;
  FIsNull := Source.FIsNull;

  if (not Source.IsNull) then
    if (CopyDataFlag) then
      begin
        FPData := MemoryManager.GetMem(FDataSize);
        Move(Source.FPData^, FPData^, FDataSize);
      end
    else
      FPData := Source.FPData;
end;//Assign


//------------------------------------------------------------------------------
// Set Data (or make link to Data)
//------------------------------------------------------------------------------
procedure TMYLDBVariant.SetData(Buffer: Pointer; Size: Integer;
  DataType: TMYLDBBaseFieldType; CopyDataFlag: boolean);
begin
  if (CopyDataFlag) then
    begin
      if ((FPData <> nil) and
          (not FIsDataLinked) and
          (Size = FDataSize)) then
      // Using Old Buffer (FPData)
      else
        begin
          Clear;
          FPData := MemoryManager.GetMem(Size);
        end
    end
  else
    begin
      Clear;
      FPData := Buffer;
    end;

  FDataType := DataType;
  FDataSize := Size;
  FIsNull := False;
  FIsDataLinked := not CopyDataFlag;
  if (CopyDataFlag) then
    Move(Buffer^, FPData^, FDataSize);
end;//SetData


//------------------------------------------------------------------------------
// Copy Data to Address
//------------------------------------------------------------------------------
function TMYLDBVariant.CopyDataToAddress(Buffer: Pointer; MaxSize: Integer): boolean;
var
  L: Integer;
begin
  if (IsNull) then
    begin
      Result := False;
    end
  else
    begin
      L := DataSize;
      if (MaxSize <> -1) then
       if (L > MaxSize) then
        raise EMYLDBException.Create(20056, ErrorABufferSizeExceeded);

      if (IsStringDataType and (L<=1)) then
        Result := False
      else
        begin
          Move(FPData^, Buffer^, L);
          Result := True;
        end;
    end;
end;//CopyDataToAddress




//------------------------------------------------------------------------------
// return (FPData = nil)
//------------------------------------------------------------------------------
function TMYLDBVariant.GetIsNull: Boolean;
begin
  Result := FIsNull or (FPData = nil);
end;//GetIsNull


//------------------------------------------------------------------------------
// Set typed Data to Variant
//------------------------------------------------------------------------------
procedure TMYLDBVariant.SetDataValue(const value; ValueType: TMYLDBBaseFieldType);
begin
  if ( (FDataType = ValueType) and
       (FPData <> nil) and
       (not IsStringDataType) and     // Assign if simple type (Integer, ...)
       (not FIsDataLinked) ) then
   begin
    Move(Value, FPData^, FDataSize)
   end
  else
   begin
    if (FPData <> nil) then
      Clear(FDataType);
    if FDataType = bftUnknown then
      FDataType := ValueType;

    // Set NULL if value=''
    if ((IsStringFieldType(ValueType) and (PChar(value) = nil)) or
        (IsWideStringFieldType(ValueType) and (Length(WideString(PWideChar(value)))=0)) or
        (IsStringFieldType(ValueType) and (not IsWideStringFieldType(ValueType)) and (SysUtils.StrLen(PChar(value))=0))) then
     begin
      FIsDataLinked := False;
      Exit;
     end;

    if FDataType = ValueType then
      AllocMemAndSetData(FDataType, Value, FPData, FDataSize)
    else
      CastAndSetData(Value, ValueType);
  end;
  FIsNull := False;
  FIsDataLinked := False;
end;//SetDataValue


//------------------------------------------------------------------------------
// Set typed Data from Variant
//------------------------------------------------------------------------------
procedure TMYLDBVariant.GetDataValue(out Value; ValueType: TMYLDBBaseFieldType);
begin
  if (not IsStringFieldType(ValueType)) then
    CheckDataForNull;

  if (IsStringFieldType(ValueType) and IsNull) then
    begin
      case ValueType of
        bftChar,
        bftVarchar:
          SetLength(String(Value), 0);
        bftWideChar,
        bftWideVarchar:
          SetLength(WideString(Value), 0)
      end;
    end
  else
    if FDataType = ValueType then
     begin
       case ValueType of
        bftChar,
        bftVarchar:
          begin
            SetLength(String(Value), SysUtils.StrLen(FPData));
            Move(PChar(FPData)^, PChar(Value)^, SysUtils.StrLen(FPData));
          end;
        bftBlob:
          begin
            SetLength(String(Value), FDataSize-1);
            Move(PChar(FPData)^, PChar(Value)^, FDataSize-1);
          end;
        bftWideChar,
        bftWideVarchar:
          begin
            SetLength(WideString(Value), Length(WideString(PWideChar(FPData))));
            Move(PWideChar(FPData)^, PWideChar(Value)^, Length(WideString(PWideChar(FPData)))*sizeof(WideChar));
          end;
        else
          CopyDataToAddress(@Value);
       end;
     end
    else
      CastResultToType(ValueType, Value);
end;//GetDataValue


//------------------------------------------------------------------------------
// Set Data for Int8 (Shortint)
//------------------------------------------------------------------------------
procedure TMYLDBVariant.SetDataAsSignedInt8(Value: Shortint);
begin
  SetDataValue(Value, bftSignedInt8);
end;//SetDataAsSignedInt8


//------------------------------------------------------------------------------
// Get Data for Int8 (Shortint)
//------------------------------------------------------------------------------
function TMYLDBVariant.GetDataAsSignedInt8: Shortint;
begin
  GetDataValue(Result, bftSignedInt8);
end;//GetDataAsSignedInt8



//------------------------------------------------------------------------------
// Set Data for Signed Int16 (Smallint)
//------------------------------------------------------------------------------
procedure TMYLDBVariant.SetDataAsSignedInt16(Value: Smallint);
begin
  SetDataValue(Value, bftSignedInt16);
end;//SetDataAsSignedInt16


//------------------------------------------------------------------------------
// Get Data for Signed Int16 (Smallint)
//------------------------------------------------------------------------------
function TMYLDBVariant.GetDataAsSignedInt16: Smallint;
begin
  GetDataValue(Result, bftSignedInt16);
end;



//------------------------------------------------------------------------------
// Set Data for Signed Int32 (Integer)
//------------------------------------------------------------------------------
procedure TMYLDBVariant.SetDataAsSignedInt32(Value: Integer);
begin
  SetDataValue(Value, bftSignedInt32);
end;//SetDataAsSignedInt32


//------------------------------------------------------------------------------
// Get Data for Signed Int32 (Integer)
//------------------------------------------------------------------------------
function TMYLDBVariant.GetDataAsSignedInt32: Integer;
begin
  GetDataValue(Result, bftSignedInt32);
end;//GetDataAsSignedInt32



//------------------------------------------------------------------------------
// Set Data for Signed Int64 (Int64)
//------------------------------------------------------------------------------
procedure TMYLDBVariant.SetDataAsSignedInt64(Value: Int64);
begin
  SetDataValue(Value, bftSignedInt64);
end;//SetDataAsSignedInt64


//------------------------------------------------------------------------------
// Get Data for Signed Int64 (Int64)
//------------------------------------------------------------------------------
function TMYLDBVariant.GetDataAsSignedInt64: Int64;
begin
  GetDataValue(Result, bftSignedInt64);
end;//GetDataAsSignedInt64


//------------------------------------------------------------------------------
// Set Data for Unsigned Int8 (Byte)
//------------------------------------------------------------------------------
procedure TMYLDBVariant.SetDataAsUnsignedInt8(Value: Byte);