连接DB，把查询结果赋给DataSet，以及更新数据库

string cnnString="Data Source=DB服务器名;user id=用户名;password=密码;initial catalog=数据库名";
SqlConnection connection=new SqlConnection(cnnString);

string sqlString="sql查询语句";
SqlCommand command=new SqlCommand(sqlString,connection);

SqlDataAdapter adapter=new SqlDataAdapter();
adapter.SelectCommand=command;

//查询结果赋给dataSet
DataSet dataSet=new DataSet();
adapter.Fill(dataSet);

//将DataSet中的更新返回数据库中
SqlCommandBuilder commandBuilder=new SqlCommandBuilder(adapter);
adapter.UpdateCommand=commandBuilder.GetUpdateCommand();
adapter.InsertCommand=commandBuilder.GetInsertCommand();
adapter.DeleteCommand=commandBuilder.GetDeleteCommand();

adapter.Update(dataSet);//进行更新