mainunit.pas

此代码提供一些标准接口供VC++以ADO方式访问SQL Server数据库。

unit MainUnit;

interface

uses
  Windows, DB, ADODB, SysUtils, ActiveX;

type
  PInt                  =       ^Integer;
  PPInt                 =       ^pInt;
  PPChar                =       ^PChar;
  PByte                 =       ^Byte;
  PWORD                 =       ^WORD;
  PDWORD                =       ^DWORD;
  PPointer              =       ^Pointer;
  PDouble               =       ^Double;
  PInt64                =       ^Int64;

function StartDB(szDBServer: PChar; bKeepConnect: Integer): Integer; cdecl;
function SelectCommand(szSql: PChar; pRetBuf: PPointer): Integer; cdecl;
function ExcuteCommand(szSql: PChar): Integer; cdecl;
function CloseDB(): Integer; cdecl;
function FreeAndNilMemory(p: PPointer): Integer; cdecl;

var
  gConnection : TAdoConnection = nil;
  
implementation

function StartDB(szDBServer: PChar; bKeepConnect: Integer): Integer;
begin
  try
    CoInitialize(nil);
    gConnection := TADOConnection.Create(nil);
    if not Assigned(gConnection) then begin
      Result := -1;
      Exit;
    end;
    gConnection.ConnectionString := Format('Provider=SQLOLEDB.1;Password=szmobile;Persist Security Info=True;User ID=szmobile;Initial Catalog=SZMOBILEPROJ;Data Source=%s', [szDBServer]);
    gConnection.LoginPrompt := False;
    if (bKeepConnect = 1) then
      gConnection.KeepConnection := True
    else
      gConnection.KeepConnection := False;
    gConnection.Connected := True;
    Result := 0;
  except
    Result := -1;
  end;
end;

function SelectCommand(szSql: PChar; pRetBuf: PPointer): Integer;
var
  AdoQuery : TADOQuery;
  //guid : TGUID;
  nStructSize, i, j : Integer;
  nRow, nPos : Integer;
  dwPos, dwStart : DWORD;
  chTmp : Char;
  nInt64 : Int64;
  //szTmp : String;
begin
  AdoQuery := nil;
  try
    AdoQuery := TADOQuery.Create(nil);
    if not Assigned(AdoQuery) then begin
      Result := -1;
      Exit;
    end;
    //CreateGUID(guid);
    //szTmp := IntToStr(guid.D1) + IntToStr(guid.D2) + IntToStr(guid.D3);
    //AdoQuery.Name := 'ADOQry_' + szTmp;
    AdoQuery.Connection := gConnection;
    AdoQuery.Prepared := True;
    AdoQuery.Close;
    AdoQuery.SQL.Text := szSql;
    AdoQuery.Open();
    if (AdoQuery.RecordCount < 1) then
      begin
        Result := 0;
        AdoQuery.Destroy;
        Exit;
      end
    else
      begin
        nStructSize := 0;
        for i := 0 to AdoQuery.FieldCount -1 do begin
          if (AdoQuery.Fields[i].DataType = ftString) then
            nStructSize := nStructSize + AdoQuery.Fields[i].DataSize -1
          else if (AdoQuery.Fields[i].DataType = ftWord) then  //(在Delphi中取出的tinyint类型为word，因此特殊处理)
            nStructSize := nStructSize + AdoQuery.Fields[i].DataSize -1
          else
            nStructSize := nStructSize + AdoQuery.Fields[i].DataSize;
        end;
        pRetBuf^ := GetMemory(AdoQuery.RecordCount * nStructSize +10);
        FillMemory(pRetBuf^, AdoQuery.RecordCount * nStructSize +10, 0);
        if (pRetBuf^ = nil) then begin
          Result := -1;
          AdoQuery.Destroy;
          Exit;
        end;

        dwStart := DWORD(pRetBuf^);
        nRow := 0;
        while not AdoQuery.Eof do begin
          dwPos := nRow * nStructSize;
          for i := 0 to AdoQuery.Fields.Count -1 do begin
            case AdoQuery.Fields[i].DataType of
              ftString :
                begin
                  if AdoQuery.Fields[i].IsNull then
                    begin
                      FillMemory(Pointer(dwStart + dwPos), AdoQuery.Fields[i].DataSize -1, 0);
                    end
                  else
                    begin
                      StrPCopy(Pointer(dwStart + dwPos), AdoQuery.Fields[i].AsString);
                      nPos := 0;
                      for j := AdoQuery.Fields[i].DataSize -3 downto 0 do begin
                        chTmp := PChar(dwStart + dwPos + DWORD(j))^;
                        if (chTmp <> Chr(32)) and (chTmp <> Chr(0)) then begin
                          PChar(dwStart + dwPos + DWORD(j) +1)^ := Chr(0);
                          nPos := dwStart + dwPos + DWORD(j);
                          Break;
                        end;
                      end;
                      if (nPos = 0) then begin
                        FillMemory(Pointer(dwStart + dwPos), AdoQuery.Fields[i].DataSize, 0);
                      end;
                    end;
                end;
              ftWord : //(在Delphi中取出的tinyint类型为word，因此特殊处理)
                begin
                  if AdoQuery.Fields[i].IsNull then
                    PByte(dwStart + dwPos)^ := 0
                  else
                    PByte(dwStart + dwPos)^ := Byte(AdoQuery.Fields[i].AsInteger);
                end;
              ftSmallint :
                begin
                  if AdoQuery.Fields[i].IsNull then
                    PWORD(dwStart + dwPos)^ := 0
                  else
                    PWORD(dwStart + dwPos)^ := WORD(AdoQuery.Fields[i].AsInteger);
                end;
              ftInteger :
                begin
                  if AdoQuery.Fields[i].IsNull then
                    PInt(dwStart + dwPos)^ := 0
                  else
                    PInt(dwStart + dwPos)^ := AdoQuery.Fields[i].AsInteger;
                end;
              ftFloat :
                begin
                  if AdoQuery.Fields[i].IsNull then
                    PDouble(dwStart + dwPos)^ := 0.0
                  else
                    PDouble(dwStart + dwPos)^ := AdoQuery.Fields[i].AsFloat;
                end;
              ftBytes, ftVarBytes, ftFixedChar :
                begin
                  if (AdoQuery.Fields[i].IsNull) then
                    FillMemory(Pointer(dwStart + dwPos), AdoQuery.Fields[i].DataSize, 0)
                  else
                    AdoQuery.Fields[i].GetData(Pointer(dwStart + dwPos));
                end;
              ftBlob :
                begin
                  FillMemory(Pointer(dwStart + dwPos), AdoQuery.Fields[i].DataSize, 0);
                end;
              ftLargeint :
                begin
                  AdoQuery.Fields[i].GetData(@nInt64);
                  PInt64(dwStart + dwPos)^ := nInt64;
                end;
            end;
            if (AdoQuery.Fields[i].DataType = ftString) then
              dwPos := dwPos + DWORD(AdoQuery.Fields[i].DataSize -1)
            else if (AdoQuery.Fields[i].DataType = ftWord) then
              dwPos := dwPos + DWORD(AdoQuery.Fields[i].DataSize) -1
            else
              dwPos := dwPos + DWORD(AdoQuery.Fields[i].DataSize);
          end;
          AdoQuery.Next;
          nRow := nRow +1;
        end;
      end;

      Result := AdoQuery.RecordCount;
  except
    Result := -1;
  end;

  if Assigned(AdoQuery) then begin
    AdoQuery.Destroy;
  end;

end;

function ExcuteCommand(szSql: PChar): Integer;
var
  AdoQuery : TADOQuery;
begin
  AdoQuery := nil;
  try
    AdoQuery := TADOQuery.Create(nil);
    if not Assigned(AdoQuery) then begin
      Result := -1;
      Exit;
    end;
    AdoQuery.Connection := gConnection;
    AdoQuery.Prepared := True;
    AdoQuery.Close;
    AdoQuery.SQL.Text := szSql;
    AdoQuery.ExecSQL();
    Result := 1;
  except
    Result := -1;
  end;

  if Assigned(AdoQuery) then begin
    AdoQuery.Destroy;
  end;
end;

function CloseDB(): Integer;
begin
  if Assigned(gConnection) then begin
    gConnection.Connected := False;
    gConnection.Destroy();
  end;
  CoUninitialize();
  Result := 1;
end;

function FreeAndNilMemory(p: PPointer): Integer;
begin
  FreeMemory(p^);
  p^ := nil;
  Result := 1;
end;


end.