用Visual C＃来修改和删除数据库记录
一 程序设计和运行的环境设置 （ ）视窗 服务器版 （ ）Microsoft Access Data Component 以上版本 ( MADC ) （ ）本文程序使用的数据库的介绍
为了方便起见 在选用数据库方面选用了本地数据库Access 当然你也可以选用其他类型的数据库 只需要更改文章后面的程序源代码中数据库的引擎 并更改对应的代码就可以了 本程序中使用的数据库名称为sample mdb 在此数据库中有一张数据表books 此数据表的结构如下 字段名称 字段类型 代表意思 Bookid 数字 序号 booktitle 文本 书籍名称 bookauthor 文本 书籍作者 bookprice 数字 价格 bookstock 数字 书架号
二 程序设计难点和应该注意的问题 在程序设计中的重点和难点就是如何用Visual C#删除记录和如何修改记录 下面就这二个问题进行必要的论述 （ ）如何用Visual C#正确删除数据表中的记录
在用Visual C#删除记录的时候要注意的是 必须从二个方面彻底删除记录 即从数据库和用Visual C#编程时产生的一个DataSet对象中彻底删除 在程序设计的时候 如果只是删除了DataSet对象中的记录信息 这种删除是一种伪删除 这是因为当他退出程序 又重新运行程序 会发现 那个要删除的记录依然还存在 这是因为DataSet对象只是对数据表的一个镜像 并不是真正的记录本身 但如果只是从数据库中删除记录 因为我们此时程序用到的数据集合是从DataSet对象中读取的 子DataSet对象中依然保存此条记录的镜像 所以就会发现 我们根本没有删除掉记录 但实际上已经删除了 此时只有退出程序 重新运行 才会发现记录已经删除了 本文使用的方法是删除以上二个方面的记录或记录镜像信息 当然你也可以使用其他的方法 譬如 首先从数据库中删除记录 然后重新建立数据连接 重新创建一个新的DataSet对象 这种方法虽然也可以达到相同目的 但显然相对繁杂些 所以本文采用的是第一种方法 直接删除 在程序中具体的实现语句如下 //连接到一个数据库 string strCon = Provider = Microsoft Jet OLEDB ; Data Source = sample mdb ; OleDbConnection myConn = new OleDbConnection ( strCon ) ; myConn Open ( ) ; string strDele = DELETE FROM books WHERE bookid= + t_bookid Text ; OleDbCommand myCommand = new OleDbCommand ( strDele myConn ) ; //从数据库中删除指定记录 myCommand ExecuteNonQuery ( ) ; //从DataSet中删除指定记录信息 myDataSet Tables [ books ] Rows [ myBind Position ] Delete ( ) ; myDataSet Tables [ books ] AcceptChanges ( ) ; myConn Close ( ) ;
（ ）用Visual C#来修改数据表中的记录 在用Visual C#修改记录和删除记录 在程序设计中大致差不多 具体的实现方式也是通过SQL语句调用来实现的 下面就是在程序中修改记录的具体语句 //连接到一个数据库 string strCon = Provider = Microsoft Jet OLEDB ; Data Source = sample mdb ; OleDbConnection myConn = new OleDbConnection ( strCon ) ; myConn Open ( ) ;
//从数据库中修改指定记录 string strUpdt = UPDATE books SET booktitle = + t_booktitle Text + bookauthor = + t_bookauthor Text + bookprice = + t_bookprice Text + bookstock = + t_bookstock Text + WHERE bookid = + t_bookid Text ;
OleDbCommand myCommand = new OleDbCommand ( strUpdt myConn ) ; myCommand ExecuteNonQuery ( ) ; myConn Close ( ) ;
（ ）在了解了如何用Visual C#删除和修改记录以后 结合《Visual C＃中轻松浏览数据库记录》一文的内容 就可以得到用Visual C#完成删除和修改数据记录的比较完整程序代码 以下是本文中介绍程序的运行后的程序界面
点击小图放大 本文中程序运行后的界面三 用Visual C#实现删除和修改数据库记录的完整源程序代码 using System ; using System Drawing ; using System ComponentModel ; using System Windows Forms ; using System Data OleDb ; using System Data ; public class DataEdit : Form { private System ComponentModel Container ponents ; private Button delete ; private Button update ; private Button lastrec ; private Button nextrec ; private Button previousrec ; private Button firstrec ; private TextBox t_bookstock ; private TextBox t_bookprice ; private TextBox t_bookauthor ; private TextBox t_booktitle ; private TextBox t_bookid ; private Label l_bookstock ; private Label l_bookprice ; private Label l_bookauthor ; private Label l_booktitle ; private Label l_bookid ; private Label label ; private System Data DataSet myDataSet ; private BindingManagerBase myBind ; private bool isBound = false ; //定义此变量 是判断组件是否已经绑定数据表中的字段
public DataEdit ( ) { // 对窗体中所需要的内容进行初始化 InitializeComponent ( ) ; //连接到一个数据库 GetConnected ( ) ; } //清除程序中用到的所有资源 public override void Dispose ( ) { base Dispose ( ) ; ponents Dispose ( ) ; } public void GetConnected ( ) { try{ //创建一个 OleDbConnection对象 string strCon = Provider = Microsoft Jet OLEDB ; Data Source = sample mdb ; OleDbConnection myConn = new OleDbConnection ( strCon ) ; string strCom = SELECT * FROM books ; //创建一个 DataSet对象 myDataSet = new DataSet ( ) ; myConn Open ( ) ; OleDbDataAdapter myCommand = new OleDbDataAdapter ( strCom myConn ) ; myCommand Fill ( myDataSet books ) ; myConn Close ( ) ; //判断数据字段是否绑定到 TextBoxes if ( !isBound ) { //以下是为显示数据记录而把数据表的某个字段绑定在不同的绑定到文本框 Text 属性上 t_bookid DataBindings Add ( Text myDataSet books bookid ) ; t_booktitle DataBindings Add ( Text myDataSet books booktitle ) ; t_bookauthor DataBindings Add ( Text myDataSet books bookauthor ) ; t_bookprice DataBindings Add ( Text myDataSet books bookprice ) ; t_bookstock DataBindings Add ( Text myDataSet books bookstock ) ; //设定 BindingManagerBase //把对象DataSet和 books 数据表绑定到此myBind对象 myBind = this BindingContext [ myDataSet books ] ; isBound = true ; } } catch ( Exception e ) { MessageBox Show ( 连接数据库发生错误为 + e ToString ( ) 错误！ ) ; } } public static void Main ( ) { Application Run ( new DataEdit ( ) ) ; } private void InitializeComponent ( ) { this ponents = new System ComponentModel Container ( ) ; this t_bookid = new TextBox ( ) ; this previousrec = new Button ( ) ; this l_bookauthor = new Label ( ) ; this delete = new Button ( ) ; this t_booktitle = new TextBox ( ) ; this t_bookauthor = new TextBox ( ) ; this t_bookprice = new TextBox ( ) ; this l_bookprice = new Label ( ) ; this t_bookstock = new TextBox ( ) ; this l_bookstock = new Label ( ) ; this l_booktitle = new Label ( ) ; this update = new Button ( ) ; this nextrec = new Button ( ) ; this lastrec = new Button ( ) ; this firstrec = new Button ( ) ; this label = new Label ( ) ; this l_bookid = new Label ( ) ; t_bookid Location = new System Drawing Point ( ) ; t_bookid Size = new System Drawing Size ( ) ;
t_booktitle Location = new System Drawing Point ( ) ; t_booktitle Size = new System Drawing Size ( ) ;
t_bookauthor Location = new System Drawing Point ( ) ; t_bookauthor Size = new System Drawing Size ( ) ;
t_bookprice Location = new System Drawing Point ( ) ; t_bookprice Size = new System Drawing Size ( ) ;
t_bookstock Location = new System Drawing Point ( ) ; t_bookstock Size = new System Drawing Size ( ) ; //以下是设定在程序中使用到的Label属性 l_bookid Location = new System Drawing Point ( ) ; l_bookid Text = 序 号 ; l_bookid Size = new System Drawing Size ( ) ; l_bookid Font = new System Drawing Font ( 宋体 f ) ; l_bookid TextAlign = System Drawing ContentAlignment MiddleCenter ; l_booktitle Location = new System Drawing Point ( ) ; l_booktitle Text = 书 名 ; l_booktitle Size = new System Drawing Size ( ) ; l_booktitle Font = new System Drawing Font ( 宋体 f ) ; l_booktitle TextAlign = System Drawing ContentAlignment MiddleCenter ; l_bookauthor Location = new System Drawing Point ( ) ; l_bookauthor Text = 作 者 ; l_bookauthor Size = new System Drawing Size ( ) ; l_bookauthor Font = new System Drawing Font ( 宋体 f ) ; l_bookauthor TextAlign = System Drawing ContentAlignment MiddleCenter ; l_bookprice Location = new System Drawing Point ( ) ; l_bookprice Text = 价 格 ; l_bookprice Size = new System Drawing Size ( ) ; l_bookprice Font = new System Drawing Font ( 宋体 f ) ; l_bookprice TextAlign = System Drawing ContentAlignment MiddleCenter ;
l_bookstock Location = new System Drawing Point ( ) ; l_bookstock Text = 书 架 号 ; l_bookstock Size = new System Drawing Size ( ) ; l_bookstock Font = new System Drawing Font ( 宋体 f ) ; l_bookstock TextAlign = System Drawing ContentAlignment MiddleCenter ;
//以下设定程序中用到的功能按钮的属性及对应的事件 delete Location = new System Drawing Point ( ) ; delete ForeColor = System Drawing Color Black ; delete Size = new System Drawing Size ( ) ; delete Font = new System Drawing Font ( 宋体 f ) ; delete Text = 删除记录 ; delete Click += new System EventHandler ( GoDelete ) ;
update Location = new System Drawing Point ( ) ; update ForeColor = System Drawing Color Black ; update Size = new System Drawing Size ( ) ; update Font = new System Drawing Font ( 宋体 f ) ; update Text = 修改记录 ; update Click += new System EventHandler ( GoUpdate ) ;
firstrec Location = new System Drawing Point ( ) ; firstrec ForeColor = System Drawing Color Black ; firstrec Size = new System Drawing Size ( ) ; firstrec Font = new System Drawing Font ( 宋体 f ) ; firstrec Text = 首记录 ; firstrec Click += new System EventHandler ( GoFirst ) ;
previousrec Location = new System Drawing Point ( ) ; previousrec ForeColor = System Drawing Color Black ; previousrec Size = new System Drawing Size ( ) ; previousrec Font = new System Drawing Font ( 宋体 f ) ; previousrec Text = 上一条 ; previousrec Click += new System EventHandler ( GoPrevious ) ;
nextrec Location = new System Drawing Point ( ) ; nextrec ForeColor = System Drawing Color Black ; nextrec Size = new System Drawing Size ( ) ; nextrec Font = new System Drawing Font ( 宋体 f ) ; nextrec Text = 下一条 ; nextrec Click += new System EventHandler ( GoNext ) ;
lastrec Location = new System Drawing Point ( ) ; lastrec ForeColor = System Drawing Color Black ; lastrec Size = new System Drawing Size ( ) ; lastrec Font = new System Drawing Font ( 宋体 f ) ; lastrec Text = 尾记录 ; lastrec Click += new System EventHandler ( GoLast ) ;
label Location = new System Drawing Point ( ) ; label Text = 用Visual C#来修改和删除数据库中的记录 ; label Size = new System Drawing Size ( ) ; label ForeColor = System Drawing SystemColors Desktop ; label Font = new System Drawing Font ( 宋体 f ) ; //设定程序的主窗体的属性 this Text = 用Visual C#来修改和删除数据库中的记录！ ; this AutoScaleBaseSize = new System Drawing Size ( ) ; this FormBorderStyle = FormBorderStyle FixedSingle ; this ClientSize = new System Drawing Size ( ) ; //在主窗体中加入组件 this Controls Add ( delete ) ; this Controls Add ( update ) ; this Controls Add ( lastrec ) ; this Controls Add ( nextrec ) ; this Controls Add ( previousrec ) ; this Controls Add ( firstrec ) ; this Controls Add ( t_bookstock ) ; this Controls Add ( t_bookprice ) ; this Controls Add ( t_bookauthor ) ; this Controls Add ( t_booktitle ) ; this Controls Add ( t_bookid ) ; this Controls Add ( l_bookstock ) ; this Controls Add ( l_bookprice ) ; this Controls Add ( l_bookauthor ) ; this Controls Add ( l_booktitle ) ; this Controls Add ( l_bookid ) ; this Controls Add ( label ) ;
} // 删除记录 对应的事件 protected void GoDelete ( object sender System EventArgs e ) { try{ //连接到一个数据库 string strCon = Provider = Microsoft Jet OLEDB ; Data Source = sample mdb ; OleDbConnection myConn = new OleDbConnection ( strCon ) ; myConn Open ( ) ; string strDele = DELETE FROM books WHERE bookid= + t_bookid Text ; OleDbCommand myCommand = new OleDbCommand ( strDele myConn ) ; //从数据库中删除指定记录 myCommand ExecuteNonQuery ( ) ; //从DataSet中删除指定记录 myDataSet Tables [ books ] Rows [ myBind Position ] Delete ( ) ; myDataSet Tables [ books ] AcceptChanges ( ) ; myConn Close ( ) ; } catch ( Exception ed ) { MessageBox Show ( 删除记录错误信息 + ed ToString ( ) 错误！ ) ; } } // 修改记录 按钮对应的事件 protected void GoUpdate ( object sender System EventArgs e ) { int i = myBind Position ; try{ //连接到一个数据库 string strCon = Provider = Microsoft Jet OLEDB ; Data Source = sample mdb ; OleDbConnection myConn = new OleDbConnection ( strCon ) ; myConn Open ( ) ;
//从数据库中修改指定记录 string strUpdt = UPDATE books SET booktitle = + t_booktitle Text + bookauthor = + t_bookauthor Text + bookprice = + t_bookprice Text + bookstock = + t_bookstock Text + WHERE bookid = + t_bookid Text ;
OleDbCommand myCommand = new OleDbCommand ( strUpdt myConn ) ; myCommand ExecuteNonQuery ( ) ; myConn Close ( ) ; } catch ( Exception ed ) { MessageBox Show ( 修改指定记录错误 + ed ToString ( ) 错误！ ) ; } myBind Position = i ; } // 尾记录 按钮对应的事件 protected void GoLast ( object sender System EventArgs e ) { myBind Position = myBind Count ; } // 下一条 按钮对应的事件 protected void GoNext ( object sender System EventArgs e ) { if ( myBind Position == myBind Count ) MessageBox Show ( 已经到尾记录！ ) ; else myBind Position += ; } // 上一条 按钮对应的事件 protected void GoPrevious ( object sender System EventArgs e ) { if ( myBind Position == ) MessageBox Show ( 已经到首记录！ ) ; else myBind Position = ; } // 首记录 按钮对应的事件 protected void GoFirst ( object sender System EventArgs e ) { myBind Position = ; } } 四 编译源程序代码 生成执行文件 得到了Data cs源程序代码以后 经过下面编译命令编译成功后 即可得到执行文件data exe csc /t:winexe /r:system windows forms dll /r:system data dll data cs
lishixinzhi/Article/program/net/201311/15222
