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MFC中简单的数据库文件操作(添加,修改,查找,删除)

Jun 07, 2016 pm 02:59 PM
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要求:新建一个数据库文件(微软的 access ) , 里面包括学生的信息学号( ID ),姓名( Name ) , 英语成绩( English ) , 在 Visual C 6.0 里新建 MFC 项目,新建学生记录类( StudentRecordSet ) , 与数据库文件绑定。在 C 里面对文件里的信息进行添加

要求:新建一个数据库文件(微软的access,里面包括学生的信息学号(ID),姓名(Name,英语成绩(English,Visual C++ 6.0里新建MFC项目,新建学生记录类(StudentRecordSet,与数据库文件绑定。在C++里面对文件里的信息进行添加,查找,输出,删除操作。

1.       首先新建一个MFC项目,这里取名为data

 2.        在项目文件里,新建一个微软的access文件,取名为source

 

MFC中简单的数据库文件操作(添加,修改,查找,删除)

3.    打开source.mdb文件,点击使用设计器创建表,在表中字段名称 向下依次输入ID  Name  English ,前两个数据类型为文本,后一个数据类型为数字。选中ID的那一行,右键,设为主键(唯一的设为主键,比如一个班里的学生,每个人都有一个学号,各不相同,是唯一的)。关闭时提示是否保存对表1的修改,点击是,另存为 表名称 source 确定。

MFC中简单的数据库文件操作(添加,修改,查找,删除)

 

4.要把该数据文件设置为数据源。具体方法为打开电脑的控制面板,在里面找到管理工具,再找到数据源,双击打开,点击添加,选择Driver do Microsoft Access(* .mdb),在弹出的对话框中数据源名  source  ,数据库选择那里选择上面我们建立的数据库文件(source.mdb.

MFC中简单的数据库文件操作(添加,修改,查找,删除)

5.接下来对MFC项目进行操作。在类视图data classes右键,new class(添加类),Type  MFC Class.     Name: StudentRecordSet   Base class: CRecordset   OK。在弹出的对话框里ODBC选择source ,RecordsetType 选择Dynaset动态,OK,这样  StudentRecordSet类就和数据库文件绑定了。

MFC中简单的数据库文件操作(添加,修改,查找,删除)

     点击鼠标左键向 source.mdb 数据库文件中存数据。

1.CDataView右键添加消息句柄,选择OnLButtonDown,进入函数void CDataView::OnLButtonDown(UINT nFlags, CPoint point)中,在里面写入下面代码:

       StudentRecordSet rs; //建立对象

       rs.Open();   //打开数据库文件

       rs.AddNew();  //添加新数据

       rs.m_ID="001";  //第一条记录的ID

       rs.m_Name="Tom";

       rs.m_English=100;

       rs.Update(); //更新

       rs.Close(); //关闭文件

编译运行有错误。1class StudentRecordSet : public CRecordset 基类CRecordset不认识,双击StudentRecordSet类,添加头文件#include 2.View类中用到了StudentRecordSet rs; //建立对象 ,类StudentRecordSet不认识,双击CDataView,加入头文件,#include “StudentRecordSet.h”,编译成功。

MFC中简单的数据库文件操作(添加,修改,查找,删除)

MFC中简单的数据库文件操作(添加,修改,查找,删除)

2.运行,点击鼠标左键,界面无任何反应,实际上rs.m_ID="001"; rs.m_Name="Tom";rs.m_English=100;数据已经存储到文件source.mdb中了,打开文件,看看,已经添加进去了。

MFC中简单的数据库文件操作(添加,修改,查找,删除)

如果继续在刚才的运行窗口点击鼠标左键,出现错误。是因为又向文件中添加一条相同的记录,但是已经设 ID为主键了,唯一,不能重复添加。

MFC中简单的数据库文件操作(添加,修改,查找,删除)

3.     如果再向文件中添加一条新纪录,需要修改如下代码的值

StudentRecordSet rs; //建立对象

       rs.Open();   //打开数据库文件

       rs.AddNew();  //添加新数据

       rs.m_ID="001";  //第一条记录的ID     修改001

       rs.m_Name="Tom";                      修改Tom

       rs.m_English=100;                       修改100

       rs.Update(); //更新

       rs.Close(); //关闭文件

这里我把 001改为002    Tom改为 Jerry  100改为99,编译运行,鼠标左键,OK,到数据库文件 source.mdb中看一看,新纪录已经被添加了。PS:添加新纪录,也可以在文件中直接添加,不用再C++里面。

MFC中简单的数据库文件操作(添加,修改,查找,删除)

MFC中简单的数据库文件操作(添加,修改,查找,删除)

②点击鼠标右键,将数据库中的信息显示出来。

1.CDataView类右键添加消息句柄,选择OnRButtonDown,进入void CDataView::OnRButtonDown(UINT nFlags, CPoint point),添加下面代码:

       StudentRecordSet rs; //建立对象

       rs.Open();

       int y=20;  //控制y坐标的变化,换行

       CString strTemp;//临时变量

       CClientDC dc(this);//客户区

       while(!rs.IsEOF())  //判断是否到文件尾

       {

              strTemp.Format("ID:%s , Name:%s , English:%d",rs.m_ID,rs.m_Name,rs.m_English);//格式化

              dc.TextOut(20,y,strTemp);//dc调用函数textout显示出内容

              rs.MoveNext(); //指针默认在第一条记录,用这句话使指针下移

              y+=20;//换行

       }

       rs.Close();

MFC中简单的数据库文件操作(添加,修改,查找,删除)

OK,编译,运行,点击鼠标右键,数据库中的内容全部显示在面板上。(不要再点击鼠标左键,否则会出现上面提到的相同的错误,鼠标左键里的代码可以先注释掉)

MFC中简单的数据库文件操作(添加,修改,查找,删除)

③修改内容以及指定内容修改

1.修改内容是对第一条记录修改的,在鼠标左键里的函数里写下面代码:

                            rs.Close(); //关闭文件*/

                      StudentRecordSet rs;

                      rs.Open();

                      rs.Edit();

                      rs.m_English=60;

                      rs.Update();

                      rs.Close();

编译运行,先点击左键,再点击右键,发现第一条记录的英语成绩已经被修改成了60

MFC中简单的数据库文件操作(添加,修改,查找,删除)

MFC中简单的数据库文件操作(添加,修改,查找,删除)

2.指定内容修改把刚才加的代码注释掉,加入以下代码:

                   StudentRecordSet rs;

                   rs.m_strFilter="ID='002'";  //ID为主键,唯一,信息过滤,ID002的那一条记录,对它进行修改

                   rs.Open();

                   rs.Edit();

                   rs.m_English=80;//修改英语成绩

                   rs.Update();

                   rs.Close();

编译,运行,左键,右键,发现ID002的英语成绩已经被修改为了 80

MFC中简单的数据库文件操作(添加,修改,查找,删除)

 

MFC中简单的数据库文件操作(添加,修改,查找,删除)

④内容的查找

还是在鼠标左键的函数里,把刚才 修改 的代码注释掉,写下面代码:

                   StudentRecordSet rs;

                   rs.m_strFilter="English=80";   //这里的意思是 要查找英语成绩为80的所有记录

                   rs.Open();

                   CClientDC dc(this);

                   CString strTemp;

                   int y=20;

                   while(!rs.IsEOF())

                   {

                     strTemp.Format("ID:%s,Name:%s,English:%d",rs.m_ID,rs.m_Name,rs.m_English);

                     dc.TextOut(20,y,strTemp); //加入了显示功能,点击左键

                     rs.MoveNext();

                     y+=20; //换行

                   }

                   rs.Close();

OK,编译,运行,点击鼠标左键,发现英语成绩为80的记录被显示。因为数据库文件中只有两条记录,有一条记录英语的成绩为80,所以这里只显示一条记录。PS(查找不能加 rs.Update()函数,这个函数只跟在加入记录和修改记录后面);

MFC中简单的数据库文件操作(添加,修改,查找,删除)

 

 

 MFC中简单的数据库文件操作(添加,修改,查找,删除)

⑤内容的删除

这里指定内容删除就不说了,和指定内容修改差不多,把rs.Edit();换成rs.Delete();

下面是全部内容删除。

方法一:

1.把鼠标左键函数里刚才写的代码注释掉,加入下面代码:

                   StudentRecordSet rs;

                   rs.Open();

                   while(!rs.IsEOF())

                   {

                     rs.Delete();  //删除记录

                     rs.MoveNext();

                   }

                   rs.Close();

OK,编译,运行。左键。查看数据库文件.access

如下:

MFC中简单的数据库文件操作(添加,修改,查找,删除)

所有数据被删除。(这种方法,效率低,编程来删除文件数据,下面方法二是让数据库文件source.mdb来删除数据,效率高)

方法二:

1.把刚才方法一的代码注释掉。

加入以下代码:

CDatabase db;

                   StudentRecordSet rs(&db);

                   CString strSql="delete from source";

                   rs.Open();

                   db.ExecuteSQL(strSql);

                   rs.Close();

编译,运行,左键单击。OK达到与方法1同样的效果,文件里的数据全部删除

MFC中简单的数据库文件操作(添加,修改,查找,删除)

 

附上左键函数的代码:

void CDataView::OnLButtonDown(UINT nFlags, CPoint point) 
{
	// TODO: Add your message handler code here and/or call default

/*	StudentRecordSet rs; //建立对象
	rs.Open();   //打开数据库文件
	rs.AddNew();  //添加新数据
	rs.m_ID="002";  //第一条记录的ID值
	rs.m_Name="Jerry";
	rs.m_English=99;
	rs.Update(); //更新
	rs.Close(); //关闭文件*/

/*	StudentRecordSet rs;
	rs.Open();
	rs.Edit();
	rs.m_English=60;
	rs.Update();
	rs.Close();*/  //修改内容

	/*StudentRecordSet rs;
	rs.m_strFilter="ID='002'";
	rs.Open();
	rs.Edit();
	rs.m_English=80;
	rs.Update();
	rs.Close();*/  //指定内容修改

	/*StudentRecordSet rs;
	rs.m_strFilter="English=80";
	rs.Open();
	CClientDC dc(this);
	CString strTemp;
	int y=20;
	while(!rs.IsEOF())
	{
		strTemp.Format("ID:%s , Name:%s , English:%d",rs.m_ID,rs.m_Name,rs.m_English);
		dc.TextOut(20,y,strTemp);
		rs.MoveNext();
		y+=20;
	}
	rs.Close();*/    //查找并显示


	/*StudentRecordSet rs;
	rs.Open();
	while(!rs.IsEOF())
	{
		rs.Delete();
		rs.MoveNext();
	}
	rs.Close();*/ //删除方法1

	CDatabase db;
	StudentRecordSet rs(&db);
	CString strSql="delete from source";
	rs.Open();
	db.ExecuteSQL(strSql);
	rs.Close(); //删除方法2
	CView::OnLButtonDown(nFlags, point);
}


 

 

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