mainform.cpp

来自「C++ BUILDER精彩编程实例集锦(源码)3 第五部分 系统编程 第六部」· C++ 代码 · 共 37 行

//---------------------------------------------------------------------------

#include <vcl.h>
#pragma hdrstop

#include "MainForm.h"
//---------------------------------------------------------------------------
#pragma package(smart_init)
#pragma resource "*.dfm"
TForm1 *Form1;
//---------------------------------------------------------------------------
__fastcall TForm1::TForm1(TComponent* Owner)
        : TForm(Owner)
{
}
//---------------------------------------------------------------------------
void __fastcall TForm1::BitBtn1Click(TObject *Sender)
{//求面积字段平均值
  TQuery* pQ=this->Query1;
  pQ->Close();
  pQ->SQL->Clear();
  pQ->SQL->Text="SELECT AVG(Area) FROM Country.db";
  pQ->Open();
  int iField=pQ->FieldCount;
  AnsiString StrFieldName;
  if(iField>0)
    StrFieldName=pQ->Fields->Fields[0]->FieldName;
  double TotalArea=pQ->FieldByName(StrFieldName)->AsFloat;
  this->Edit1->Text=FloatToStr(TotalArea);
  pQ->Close();
  pQ->SQL->Clear();
  pQ->SQL->Text="SELECT * FROM Country.db";
  pQ->Open();
}
//---------------------------------------------------------------------------