c#数据库与TXT导入导出的实例

     private void button1_click(object sender, eventargs e)        
     {            
     if (openfiledialog1.showdialog() == dialogresult.ok)  
     {         
     using (filestream fs = file.openread(openfiledialog1.filename)) 
     {              
     using (streamreader sr = new streamreader(fs, system.text.encoding.getencoding("gb2312")))   
     {
     //<span style="color:#3333ff;">必需设置字符编码system.text.encoding.getencoding("gb2312")，
     不然string name = arr[0]中的name就是乱码</span>                           using (sqlconnection conn = new sqlconnection(@"data source=.\sqlexpress;attachdbfilename='|datadirectory|\dd.mdf';
     integrated security=true;user instance=true"))  
     {
     //<span style="color:#3333ff;">datadirectory指的是数据库的绝对路径，winform里面的program.cs必需添加代码，否则是.net是找到的数据库是有问题的，实在不懂可以去博客园自己去看看why</span>                            
     conn.open();                    
     using (sqlcommand cmd = conn.createcommand())      
     {                         
     cmd.commandtext = "insert into t_persons values(@name,@age)";
     string line = "";      
     while ((line = sr.readline()) != null)  
     {                
     string[] arr = line.split('|');      
     string name = arr[0];           
     int age = convert.toint32(arr[1]); 
     cmd.parameters.clear();//别忘了         
     cmd.parameters.add(new sqlparameter("name", name)); 
     cmd.parameters.add(new sqlparameter("age", age));  
     cmd.executenonquery();       
     }                    
     }                    
     }                   
     }               
     }               
     messagebox.show("txt导入数据库成功!");   
     }               
     }        
     private void button2_click(object sender, eventargs e)    
     {            
     if (savefiledialog1.showdialog() == dialogresult.ok)     
     {                 
     using (filestream fs = file.openwrite(savefiledialog1.filename)) 
     {                  
     using (streamwriter sw = new streamwriter(fs, system.text.encoding.getencoding("gb2312")))    
     {                     
     using (sqlconnection conn = new sqlconnection(@"data source=.\sqlexpress;attachdbfilename='|datadirectory|\dd.mdf';integrated security=true;user instance=true"))                         
     {                         
     conn.open();       
     using (sqlcommand cmd = conn.createcommand())     
     {                             
     cmd.commandtext = "select * from t_persons";   
     using (sqldatareader sdr = cmd.executereader())    
     {                                            
     while (sdr.read())              
     {                              
     string name = sdr.getstring(sdr.getordinal("name"));
     int age = sdr.getint32(sdr.getordinal("age"));  
     string line =name+"|"+age;                     
     sw.writeline(line);                          
     sw.flush();                       
     }                                     
     }                      
     }                 
     }                  
     }             
     }          
     messagebox.show("导出数据到txt成功！");  
     }        
     }
     </span> 

这是要在program.cs文件中添加的代码，它只对winform和win控制台有效：

static void main()        
{          
string datadir = appdomain.currentdomain.basedirectory;      
if (datadir.endswith(@"\bin\debug\") || datadir.endswith(@"\bin\release\"))  
{                
datadir = system.io.directory.getparent(datadir).parent.parent.fullname;  
appdomain.currentdomain.setdata("datadirectory", datadir);    
}               
application.enablevisualstyles(); 
application.setcompatibletextrenderingdefault(false);    
application.run(new form1());    
}