c#数据库代码（经测试）.txt

VB/VC/C#操作数据库的代码

C#访问ACCESS数据库
//安装jet4后不出现异常
using System;
using System.Data.OleDb;
class StringExc
    {
        public static void Main()
        {int a;
//创建数据库连接     
  System.Data.OleDb.OleDbConnection   aConnection=new OleDbConnection(@"Provider=Microsoft.Jet.OLEDB.4.0;Data 

Source=H:\\Data阅读\\db1.mdb");     
    aConnection.Open();
  //创建command对象并保存sql查询语句     
  //System.Data.OleDb.OleDbCommand   aCommand=new OleDbCommand(@"select count(*) from R",aConnection);     
OleDbCommand aCommand= aConnection.CreateCommand();
aCommand.CommandText= @"select count(*) As rowNum from R"; 
 
OleDbDataReader reader=aCommand.ExecuteReader(); 
  reader.Read();
  a=Convert.ToInt32(reader["rowNum"]);   
  Console.WriteLine(a);//6 ，表R中有6条记录   
  
  //关闭连接,这很重要     
  aConnection.Close();     
        }
    }

G:\test>2
This is the returned data from R table
A1,b1,6
A1,b2,6
A2,b3,8
A2,b4,11
AA,bb,99
AAA,bbb,999
using System;
using System.Data.OleDb;
class StringExc
    {
        public static void Main()
        {
//创建数据库连接     
  System.Data.OleDb.OleDbConnection   aConnection=new OleDbConnection(@"Provider=Microsoft.Jet.OLEDB.4.0;Data 

Source=H:\\Data阅读\\db1.mdb");     
  //创建command对象并保存sql查询语句     
System.Data.OleDb.OleDbCommand   aCommand=new OleDbCommand(@"select * from R",aConnection);     
try
{
aConnection.Open();
//创建datareader 对象来连接到表单R
OleDbDataReader aReader = aCommand.ExecuteReader();
Console.WriteLine("This is the returned data from R table");
//循环遍历数据库
while(aReader.Read())
{
Console.WriteLine("{0},{1},{2}",aReader.GetString(0),aReader.GetString(1),aReader.GetInt32(2).ToString());
//或Console.WriteLine("{0},{1},{2}",aReader["A"],aReader["B"],aReader["C"].ToString());
} 

//关闭reader对象
aReader.Close();

//关闭连接,这很重要
aConnection.Close();
}

//一些通常的异常处理
catch(OleDbException e)
{
Console.WriteLine("Error: {0}", e.Errors[0].Message);
}
}
}

C#连接SQL Server
程序代码片断:
//使用DataAdapter进行增删改+
private string strCon = @"Data Source=.\SQLEXPRESS;Initial catalog=D:\math.mdf;Integrated Security=SSPI;User Instance=True";
//private string strCon=@"Data Source=.\SQLEXPRESS;AttachDbFilename=D:\math.mdf;Integrated Security=True;Connect Timeout=30;User Instance=True";
private SqlConnection objSqlConnection;
private SqlDataAdapter objSqlDataAdapter;
//插入
string strSql = "insert into Table1 values('111','222','333')";
objSqlConnection.Open();
objSqlDataAdapter.InsertCommand=new SqlCommand(strSql,objSqlConnection);
objSqlDataAdapter.InsertCommand.ExecuteNonQuery();
MessageBox.Show("插入成功!");
//更新
string strSql = "update Table1 set 类别='几何原本',内容='几何基础'where 标题='111'";
objSqlConnection.Open();
objSqlDataAdapter.UpdateCommand=new SqlCommand(strSql,objSqlConnection);
objSqlDataAdapter.UpdateCommand.ExecuteNonQuery();	
MessageBox.Show("更新成功!");
//删除
string strSql = "delete from Table1 where 标题='111';";
objSqlConnection.Open();
objSqlDataAdapter.DeleteCommand=new SqlCommand(strSql,objSqlConnection);
int count=objSqlDataAdapter.DeleteCommand.ExecuteNonQuery();
MessageBox.Show("删除"+count.ToString()+"条数据!");