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C#数据库編程2

2024-07-21 02:23:40
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四.插入数据记录: </p><p>  对数据库进行插入记录操作和删除记录操作基本的思路是一致的,就是通过ado.net首先插入数据记录到数据库,然后对"dataset"对象进行必要的修改。下列代码就是以access 2000数据库为模型修改当前记录的代码: </p><p>protected void update_record ( object sender , system.eventargs e )
{

int i = mybind.position ;

try{

file://连接到一个数据库

string strcon = " provider = microsoft.jet.oledb.4.0 ; data source = db.mdb " ;

oledbconnection myconn = new oledbconnection ( strcon ) ;

myconn.open ( ) ;

mydataset.tables [ "person" ] . rows [ mybind.position ] . beginedit ( ) ;

file://从数据库中修改指定记录

string strupdt = " update person set xm = '"

+ t_xm.text + "' , xb = '"

+ t_xb.text + "' , nl = "

+ t_nl.text + " , zip = "

+ t_books.text + " where id = " + t_id.text ;

oledbcommand mycommand = new oledbcommand ( strupdt , myconn ) ;

mycommand.executenonquery ( ) ;

mydataset.tables [ "person" ] . rows [ mybind.position ] . endedit ( ) ;

mydataset.tables [ "person" ] . acceptchanges ( ) ;

myconn.close ( ) ;

}

catch ( exception ed )

{

messagebox.show ( "修改指定记录错误: " + ed.tostring ( ) , "错误!" ) ;

}

mybind.position = i ;

} </p><p>  由于对sql server 2000数据记录修改操作和access 2000数据记录修改操作的差异只在于不同的数据链接,具体的代码可以参考"删除数据记录"中的代码,在这里就不提供了。



五.插入数据记录:



  和前面二种操作在思路是一致的,就是通过ado.net首先插入数据记录到数据库,然后对"dataset"对象进行必要的修改。下列代码就是以access 2000数据库为模型插入一条数据记录的代码



protected void insert_record ( object sender , system.eventargs e )

{

try

{

file://判断所有字段是否添完,添完则执行,反之弹出提示

if ( t_id.text != "" && t_xm.text != "" && t_xb.text != "" && t_nl.text != "" && t_books.text != "" )

{

string myconn1 = " provider = microsoft.jet.oledb.4.0 ; data source = db.mdb" ;

oledbconnection myconn = new oledbconnection ( myconn1 ) ;

myconn.open ( ) ;

string strinsert = " insert into person ( id , xm , xb , nl , zip ) values ( " ;

strinsert += t_id.text + ", '" ;

strinsert += t_xm.text + "', '" ;

strinsert += t_xb.text + "', " ;

strinsert += t_nl.text + ", " ;

strinsert += t_books.text + ")" ;

oledbcommand inst = new oledbcommand ( strinsert , myconn ) ;

inst.executenonquery ( ) ;

myconn.close ( ) ;

mydataset.tables [ "person" ] . rows [ mybind.position ] . beginedit ( ) ;

mydataset.tables [ "person" ] . rows [ mybind.position ] . endedit ( ) ;

mydataset.tables [ "person" ] . acceptchanges ( ) ;

}

else

{

messagebox.show ( "必须填满所有字段值!" , "错误!" ) ;

}

}

catch ( exception ed )

{

messagebox.show ( "保存数据记录发生 " + ed.tostring ( ) , "错误!" ) ;

}

}



  同样对sql server 2000数据库进行插入记录操作和access 2000数据库插入记录操作的差异也只在于不同的数据链接,具体的代码可以参考"删除数据记录"中的代码,在这里就不提供了。

  六.visual c#数据库编程的完成源代码和程序运行的主界面:



  掌握了上面要点,编写一个完整的数据库编程的程序就显得非常容易了,下面是visual c#进行数据库编程的完整代码(data01.cs),此代码是以access 2000数据库为模型设计的,具体如下:



using system ;

using system.drawing ;

using system.componentmodel ;

using system.windows.forms ;

using system.data.oledb ;

using system.data ;



public class data : form

{

private system.componentmodel.container components = null ;

private button lastrec ;

private button nextrec ;

private button previousrec ;

private button firstrec ;

private textbox t_books ;

private textbox t_nl ;

private combobox t_xb ;

private textbox t_xm ;

private textbox t_id ;

private label l_books ;

private label l_nl ;

private label l_xb ;

private label l_xm ;

private label l_id ;

private label label1 ;

private dataset mydataset ;

private button button1 ;

private button button2 ;

private button button3 ;

private button button4 ;

private bindingmanagerbase mybind ;



public data ( )

{

file://连接到一个数据库

getconnected ( ) ;

// 对窗体中所需要的内容进行初始化

initializecomponent ( ) ;

}

file://清除在程序中使用过的资源

protected override void dispose( bool disposing )

{

if( disposing )

{

if ( components != null )

{

components.dispose ( ) ;

}

}

base.dispose( disposing ) ;

}

public static void main ( )

{

application.run ( new data ( ) ) ;

}

public void getconnected ( )

{

try

{

file://创建一个 oledbconnection

string strcon = " provider = microsoft.jet.oledb.4.0 ; data source = db.mdb" ;

oledbconnection myconn = new oledbconnection ( strcon ) ;

string strcom = " select * from person " ;

file://创建一个 dataset

mydataset = new dataset ( ) ;



myconn.open ( ) ;

file://用 oledbdataadapter 得到一个数据集

oledbdataadapter mycommand = new oledbdataadapter ( strcom , myconn ) ;

file://把dataset绑定books数据表

mycommand.fill ( mydataset , "person" ) ;

file://关闭此oledbconnection

myconn.close ( ) ;

}

catch ( exception e )

{

messagebox.show ( "连接错误! " + e.tostring ( ) , "错误" ) ;

}

}

private void initializecomponent ( )

{



file://添加控件,略



this.name = "data" ;

this.text = "visual c#的数据库编程!" ;

this.resumelayout(false) ;

mybind = this.bindingcontext [ mydataset , "person" ] ;

}

protected void new_record ( object sender , system.eventargs e )

{

t_id.text = ( mybind.count + 1 ).tostring ( ) ;

t_xm.text = "" ;

t_xb.text = "" ;

t_nl.text = "" ;

t_books.text = "" ;

}

protected void insert_record ( object sender , system.eventargs e )

{

try

{

file://判断所有字段是否添完,添完则执行,反之弹出提示

if ( t_id.text != "" && t_xm.text != "" && t_xb.text != "" && t_nl.text != "" && t_books.text != "" )

{

string myconn1 = " provider = microsoft.jet.oledb.4.0 ; data source = db.mdb" ;

oledbconnection myconn = new oledbconnection ( myconn1 ) ;

myconn.open ( ) ;

string strinsert = " insert into person ( id , xm , xb , nl , zip ) values ( " ;

strinsert += t_id.text + ", '" ;

strinsert += t_xm.text + "', '" ;

strinsert += t_xb.text + "', " ;

strinsert += t_nl.text + ", " ;

strinsert += t_books.text + ")" ;

oledbcommand inst = new oledbcommand ( strinsert , myconn ) ;

inst.executenonquery ( ) ;

myconn.close ( ) ;

mydataset.tables [ "person" ] . rows [ mybind.position ] . beginedit ( ) ;

mydataset.tables [ "person" ] . rows [ mybind.position ] . endedit ( ) ;

mydataset.tables [ "person" ] . acceptchanges ( ) ;

}

else

{

messagebox.show ( "必须填满所有字段值!" , "错误!" ) ;

}

}

catch ( exception ed )

{

messagebox.show ( "保存数据记录发生 " + ed.tostring ( ) , "错误!" ) ;

}

}

protected void update_record ( object sender , system.eventargs e )

{

int i = mybind.position ;

try{

file://连接到一个数据库

string strcon = " provider = microsoft.jet.oledb.4.0 ; data source = db.mdb " ;

oledbconnection myconn = new oledbconnection ( strcon ) ;

myconn.open ( ) ;

mydataset.tables [ "person" ] . rows [ mybind.position ] . beginedit ( ) ;

file://从数据库中修改指定记录

string strupdt = " update person set xm = '"

+ t_xm.text + "' , xb = '"

+ t_xb.text + "' , nl = "

+ t_nl.text + " , zip = "

+ t_books.text + " where id = " + t_id.text ;

oledbcommand mycommand = new oledbcommand ( strupdt , myconn ) ;

mycommand.executenonquery ( ) ;

mydataset.tables [ "person" ] . rows [ mybind.position ] . endedit ( ) ;

mydataset.tables [ "person" ] . acceptchanges ( ) ;

myconn.close ( ) ;

}

catch ( exception ed )

{

messagebox.show ( "修改指定记录错误: " + ed.tostring ( ) , "错误!" ) ;

}

mybind.position = i ;

}



protected void delete_record ( object sender , system.eventargs e )

{

dialogresult r = messagebox.show ( "是否删除当前记录!" , "删除当前记录!" , messageboxbuttons.yesno , messageboxicon.question ) ;

int ss = ( int ) r ;

  if ( ss == 6 ) // 按动"确定"按钮

{

try{

file://连接到一个数据库

string strcon = " provider = microsoft.jet.oledb.4.0 ; data source = db.mdb " ;

oledbconnection myconn = new oledbconnection ( strcon ) ;

myconn.open ( ) ;

string strdele = "delete from person where id= " + t_id.text ;

oledbcommand mycommand = new oledbcommand ( strdele , myconn ) ;

file://从数据库中删除指定记录

mycommand.executenonquery ( ) ;

file://从dataset中删除指定记录

mydataset.tables [ "person" ] . rows [ mybind.position ] . delete ( ) ;

mydataset.tables [ "person" ] . acceptchanges ( ) ;

myconn.close ( ) ;

}

catch ( exception ed )

{

messagebox.show ( "删除记录错误信息: " + ed.tostring ( ) , "错误!" ) ;

}

}

}

file://按钮"尾记录"对象事件程序

protected void golast ( object sender , system.eventargs e )

{

mybind.position = mybind.count - 1 ;

}



file://按钮"下一条"对象事件程序

protected void gonext ( object sender , system.eventargs e )

{

if ( mybind.position == mybind.count -1 )

messagebox.show ( "已经到了最后一条记录!", "信息提示!" , messageboxbuttons.ok , messageboxicon.information ) ;

else

mybind.position += 1 ;

}

file://按钮"上一条"对象事件程序

protected void goprevious ( object sender , system.eventargs e )

{

if ( mybind.position == 0 )

messagebox.show ( "已经到了第一条记录!" , "信息提示!" , messageboxbuttons.ok , messageboxicon.information ) ;

else

mybind.position -= 1 ;

}

file://按钮"首记录"对象事件程序

protected void gofirst ( object sender , system.eventargs e )

{

mybind.position = 0 ;

}

}





  对于以sql server 2000数据库为模型的程序代码,只要把data01.cs中的数据链接,即:

string myconn1 = " provider = microsoft.jet.oledb.4.0 ; data source = db.mdb" ;



  改换成:

string strcon = "provider = sqloledb.1 ; persist security info = false ; user id = sa ; initial catalog = data1 ; data source = server1 " ;



  注释:此数据链接代表的意思是:打开sql server数据库,服务器名称为server1,数据库为data1

就可以得到visual c#针对sql server 2000数据库为模板编程的完成源程序代码了。所以本文就不再提供了。



  七.总结:



  数据库编程始终是程序编程内容中的一个重点和难点。而以上介绍的这些操作又是数据库编程中最为基本,也是最为重要的内容。那些复杂的编程无非是以上这些处理的若干个叠加。






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