main.cpp

来自「Direct Oracle Access 非常好的Oracle数据库直接访问组」· C++ 代码 · 共 106 行

// Direct Oracle Access - Department grid demo
// Allround Automations
// [e-mail]
// http://www.allroundautomations.nl
//
// This application demonstrates:
// - Connecting to a database
// - Selecting and updating data using variables
// - Displaying queried data in a grid
//---------------------------------------------------------------------------
#include <vcl\vcl.h>
#pragma hdrstop

#include "Main.h"
//---------------------------------------------------------------------------
#pragma link "Grids"
#pragma link "Oracle"
#pragma resource "*.dfm"
TMainForm *MainForm;
//---------------------------------------------------------------------------
__fastcall TMainForm::TMainForm(TComponent* Owner)
	: TForm(Owner)
{
}
//---------------------------------------------------------------------------
void __fastcall TMainForm::ConnectBtnClick(TObject *Sender)
{
  // Log on or off
  if (MainSession->Connected) MainSession->LogOff(); else MainLogon->Execute();
  // The button shows if we're connected
  ConnectBtn->Down = MainSession->Connected;
}
//---------------------------------------------------------------------------
void __fastcall TMainForm::QueryBtnClick(TObject *Sender)
{
int Row;
  // Setup titles
  DeptGrid->Cells[0][0] = "Number";
  DeptGrid->Cells[1][0] = "Name";
  DeptGrid->Cells[2][0] = "Location";
  Row = 1;
  // Execute the query
  // SelectQuery->SQL = select * from dept
  //                    order by deptno
  try
  {
    SelectQuery->Execute();
    // Fill the grid, mark each row unchanged
    while (!SelectQuery->Eof)
    {
      DeptGrid->Cells[0][Row] = SelectQuery->Field("DEPTNO");
      DeptGrid->Cells[1][Row] = SelectQuery->Field("DNAME");
      DeptGrid->Cells[2][Row] = SelectQuery->Field("LOC");
      DeptGrid->Cells[3][Row] = "UNCHANGED";
      SelectQuery->Next();
      Row++;
    }
  }
  catch (EOracleError &E)
  {
     if (E.ErrorCode == 942)
       Application->MessageBox("You must install the demo tables first", "Error", IDOK);
     else
       Application->ShowException(&E);
  }
  // Adjust the grid
  DeptGrid->RowCount = Row + 1;
}
//---------------------------------------------------------------------------
void __fastcall TMainForm::DeptGridSetEditText(TObject *Sender, int ACol,
	int ARow, const AnsiString Value)
{
  // Mark row as changed
  DeptGrid->Cells[3][ARow] = "CHANGED";
}
//---------------------------------------------------------------------------
void __fastcall TMainForm::CommitBtnClick(TObject *Sender)
{
int Row;
  for (Row = 1; Row < DeptGrid->RowCount; Row++)
  {
    // Execute an update statement for each changed row
    // UpdateQuery->SQL = update dept
    //                    set dname = :dname, loc = :loc
    //                    where deptno = :deptno
    if (DeptGrid->Cells[3][Row] == "CHANGED")
    try
    {
      // Set the query variables to the new values
      UpdateQuery->SetVariable("DEPTNO", DeptGrid->Cells[0][Row]);
      UpdateQuery->SetVariable("DNAME",  DeptGrid->Cells[1][Row]);
      UpdateQuery->SetVariable("LOC",    DeptGrid->Cells[2][Row]);
      // Update it
      UpdateQuery->Execute();
      // Mark row unchanged
      DeptGrid->Cells[3][Row] = "UNCHANGED";
    }
    catch (EOracleError &E)
    {
      Application->ShowException(&E);
    }
  }
  // Commit all updates
  MainSession->Commit();
}
//---------------------------------------------------------------------------