mainunit.cpp

Direct Oracle Access 非常好的Oracle数据库直接访问组件包 支持个版本的Delphi及C++ Builder 有源码

// Direct Oracle Access - ObjectGrid
// Allround Automations
// [e-mail]
// http://www.allroundautomations.nl
//
// This application demonstrates:
// - Manipulation of persistent objects
//---------------------------------------------------------------------------
#include <vcl\vcl.h>
#pragma hdrstop

#include "MainUnit.h"
//---------------------------------------------------------------------------
#pragma link "Grids"
#pragma link "Oracle"
#pragma resource "*.dfm"
TMainForm *MainForm;
//---------------------------------------------------------------------------
__fastcall TMainForm::TMainForm(TComponent* Owner)
	: TForm(Owner)
{
}
//---------------------------------------------------------------------------
// Execute a SQL command
void __fastcall TMainForm::ExecuteSQL(AnsiString SQLText)
{
  TOracleQuery *Q;

  Q = new TOracleQuery(0);
  try
  {
    Q->Session   = MainSession;
    Q->Cursor    = crSQLWait;
    Q->SQL->Text = SQLText;
    Q->Execute();
  }
  catch ( ... )
  {
    Q->Free();
  }
}
//---------------------------------------------------------------------------
// Create objects for demo
Boolean __fastcall TMainForm::CreateObjects()
{
  // Ask if objects are to be created
  if (MessageDlg("Create demo objects?", mtConfirmation, TMsgDlgButtons() << mbYes << mbNo, 0) == mrNo)
  {
    return(false);
  }
  else
  {
    // Create the address object
    ExecuteSQL("create type TDemoAddress as object( "
               "  Street varchar2(30), "
               "  City   varchar2(30), "
               "  State  varchar2(2), "
               "  Zip    number(5)) ");
    // Create the person object
    ExecuteSQL("create type TDemoPerson as object( "
               "  Name      varchar2(30), "
               "  Birthday  date, "
               "  Address   TDemoAddress, "
               "  member function Age return integer, "
               "  pragma restrict_references(Age, rnps, wnds)) ");
    // Create the person object body with method 'Age'
    ExecuteSQL("create type body TDemoPerson is "
               "  member function Age return integer is "
               "  begin "
               "    return(floor(months_between(Sysdate, Birthday) / 12)); "
               "  end; "
               "end; ");
    // Create the table
    ExecuteSQL("create table DemoPersons of TDemoPerson");
    // Create two initial object instances
    ExecuteSQL("insert into DemoPersons values( "
               "'John Smith', to_date('01/12/1954', 'dd/mm/yyyy'), "
               "TDemoAddress('17 Centennial Drive', 'Peabody', 'MA', 17554))");
    ExecuteSQL("insert into DemoPersons values( "
               "'David Jones', to_date('17/08/1961', 'dd/mm/yyyy'), "
               "TDemoAddress('67 Stewart Drive', 'Willowbrook', 'IL', 61773))");
    // Commit it
    MainSession->Commit();
    return(true);
  }
}
//---------------------------------------------------------------------------
// Drop objects for demo
void __fastcall TMainForm::DropObjects()
{
  // Drop the table
  ExecuteSQL("drop table DemoPersons");
  // Drop the person object
  ExecuteSQL("drop type TDemoPerson");
  // Drop the address object
  ExecuteSQL("drop type TDemoAddress");
}
//---------------------------------------------------------------------------
// Go to a cell in the grid
void __fastcall TMainForm::GotoCell(int Col, int Row)
{
  Moving = true;
  Grid->Row = Row;
  Grid->Col = Col;
  Moving = false;
}
//---------------------------------------------------------------------------
// Return the attribute name of a column of the grid
AnsiString __fastcall TMainForm::ColAttrName(int Col)
{
  switch(Col)
  {
    case 0: return("Name");
    case 1: return("Birthday");
    case 2: return("Address.Street");
    case 3: return("Address.City");
    case 4: return("Address.State");
    case 5: return("Address.Zip");
    case 6: return("Age");
  }
  return("Unknown");
}
//---------------------------------------------------------------------------
// Free all objects on the list
void __fastcall TMainForm::FreeObjects()
{
  int i;
  TOracleObject *Person;

  for (i = 0; i < ObjectList->Count; i++)
  {
    Person = (TOracleObject *)ObjectList->Items[i];
    Person->Free();
  }
  ObjectList->Clear();
  for (i = 0; i < DeletedList->Count; i++)
  {
    Person = (TOracleObject *)DeletedList->Items[i];
    Person->Free();
  }
  DeletedList->Clear();
}
//---------------------------------------------------------------------------
// Query the objects and place them in the grid
void __fastcall TMainForm::QueryObjects()
{
  TOracleObject *Person;
  int Row;

  GotoCell(0, 1);
  FreeObjects();
  try
  {
    Query->Execute();
  }
  catch (EOracleError &E)
  {
    if (E.ErrorCode == 942)
    {
      if (CreateObjects()) Query->Execute(); else return;
    }
  }
  Row = 1;
  while (!Query->Eof)
  {
    Person = Query->RefField("Person")->Pin(poRecent, plNone);
    Grid->Cells[0][Row] = Person->GetAttr("Name");
    Grid->Cells[1][Row] = Person->GetAttr("Birthday");
    Grid->Cells[2][Row] = Person->GetAttr("Address.Street");
    Grid->Cells[3][Row] = Person->GetAttr("Address.City");
    Grid->Cells[4][Row] = Person->GetAttr("Address.State");
    Grid->Cells[5][Row] = Person->GetAttr("Address.Zip");
    Grid->Cells[6][Row] = Person->CallMethod("Age", OPENARRAY(Variant, (parNone)));

    Grid->Cells[7][Row] = "";
    ObjectList->Add(Person);
    Query->Next();
    Row++;
  }
  Grid->RowCount = Row;
}
//---------------------------------------------------------------------------
// Copy the value of the current cell to the object attribute
Boolean __fastcall TMainForm::CellToAttribute()
{
  TOracleObject *Person;
  AnsiString AttrName;
  Variant AttrValue;

  if (Moving) return(true);
  // Get the person object
  Person = (TOracleObject *)ObjectList->Items[Grid->Row - 1];
  // Determine the attribute name and value of this cell
  AttrName  = ColAttrName(Grid->Col);
  if (Grid->Cells[Grid->Col][Grid->Row] == "")
    AttrValue = Null;
  else
    AttrValue = Grid->Cells[Grid->Col][Grid->Row];
  try
  {
    // Try to set the attribute
    Person->SetAttr(AttrName, AttrValue);
    // If the birthday changes, recalculate the age
    if (AttrName == "Birthday")
      Grid->Cells[6][Grid->Row] = Person->CallMethod("Age", OPENARRAY(Variant, (parNone)));
  }
  catch (EOracleError &E)
  {
    ShowMessage(E.Message);
    return(false);
  }
  return(true);
}
//---------------------------------------------------------------------------
void __fastcall TMainForm::DropBtnClick(TObject *Sender)
{
  DropObjects();
}
//---------------------------------------------------------------------------
void __fastcall TMainForm::RefreshBtnClick(TObject *Sender)
{
  MainSession->Rollback();
  QueryObjects();
}
//---------------------------------------------------------------------------
void __fastcall TMainForm::FormCreate(TObject *Sender)
{
  ObjectList  = new TList;
  DeletedList = new TList;
  MainLogon->Execute();
  if (!MainSession->Connected)
  {
    Application->Terminate();
  }
  else
  {
    if (!OCI80)
    {
      ShowMessage("This demo requires Net8, which is not detected on this PC.");
      Application->Terminate();
    }
    else
    {
      Moving = false;
      Grid->Cells[0][0]  = "Name";
      Grid->ColWidths[0] = 150;
      Grid->Cells[1][0]  = "Birthday";
      Grid->ColWidths[1] = 80;
      Grid->Cells[2][0]  = "Street";
      Grid->ColWidths[2] = 150;
      Grid->Cells[3][0]  = "City";
      Grid->ColWidths[3] = 150;
      Grid->Cells[4][0]  = "State";
      Grid->ColWidths[4] = 40;
      Grid->Cells[5][0]  = "Zip";
      Grid->ColWidths[5] = 40;
      Grid->Cells[6][0]  = "Age";
      Grid->ColWidths[6] = 40;
      QueryObjects();
    }
  }
}
//---------------------------------------------------------------------------
void __fastcall TMainForm::FormDestroy(TObject *Sender)
{
  FreeObjects();
  ObjectList->Free();
  DeletedList->Free();
}
//---------------------------------------------------------------------------
void __fastcall TMainForm::GridSelectCell(TObject *Sender, int Col, int Row,
	bool &CanSelect)
{
  if (Col == 6)
    CanSelect = false;
  else
    CanSelect = CellToAttribute();
}
//---------------------------------------------------------------------------
void __fastcall TMainForm::CommitBtnClick(TObject *Sender)
{
  int i;
  TOracleObject *Person;

  if (CellToAttribute())
  {
    // Committing will flush all new, modified and deleted objects
    MainSession->Commit();
    // After this, the Deleted objects can be freed
    for (i = 0; i < DeletedList->Count; i++)
    {
      Person = (TOracleObject *)DeletedList->Items[i];
      Person->Free();
    }
    DeletedList->Clear();
    // Mark all objects inserted
    Grid->Cols[7]->Clear();
  }
}
//---------------------------------------------------------------------------
void __fastcall TMainForm::AddBtnClick(TObject *Sender)
{
  TOracleObject *Person;

  if (CellToAttribute())
  {
    // Add a row at the end of the grid
    Grid->RowCount = Grid->RowCount + 1;
    GotoCell(0, Grid->RowCount - 1);
    Grid->Rows[Grid->Row]->Clear();
    Grid->Cells[7][Grid->Row] = "*";
    // Create a new persistent object
    Person = new TOracleObject(MainSession, "TDemoPerson", "DemoPersons");
    // Add it to the list
    ObjectList->Add(Person);
  }
}
//---------------------------------------------------------------------------
void __fastcall TMainForm::DeleteBtnClick(TObject *Sender)
{
  int Row;
  TOracleObject *Person;

  // Find the object and remove it from the list
  Person = (TOracleObject *)ObjectList->Items[Grid->Row - 1];
  ObjectList->Delete(Grid->Row - 1);
  // If the object was not yet flushed, just free it
  if (Grid->Cells[7][Grid->Row] == "*")
  {
    // Mark it not modified so that it will not be flushed
    Person->Modified = false;
    // Free it
    Person->Free();
  }
  else
  {
    // Mark the object deleted
    Person->Delete();
    // Move the object from the object list to the deleted list
    DeletedList->Add(Person);
  }
  // Remove the Row from the grid
  for (Row = Grid->Row; Row <= Grid->RowCount - 1; Row++)
    Grid->Rows[Row]->Assign(Grid->Rows[Row + 1]);
  // Move the cursor if it's going to be off the grid
  if (Grid->Row >= Grid->RowCount - 1) GotoCell(Grid->Col, Grid->RowCount - 2);
  Grid->RowCount = Grid->RowCount - 1;
}
//---------------------------------------------------------------------------