数据库的连接问题

1.在配置文件里面 <configuration>
  <appSettings>
    <add key="ConnectionString"

value="server=localhost;database=myWebDB;

UID=sa;pwd=123321"></add>
  </appSettings>  <connectionStrings/>

在页面后台里面

SqlConnection myConnection = new

SqlConnection(ConfigurationSettings.AppSettings

["ConnectionString"]);
        myConnection.Open();

2.直接在一个类里面写，然后调用这个连接

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data;
using System.Data.SqlClient;

namespace MyOfficeBBL
{
  public class GetConnection
    {
        private static SqlConnection _connection;
      /// <summary>
      /// 获取数据库连接桥
      /// </summary>
        private static SqlConnection Connection
        {
            get
            {
                string connectionString = "Data Source=.;Initial Catalog=MyOffice;Integrated Security=True";
                if (_connection == null)
                {
                    _connection = new SqlConnection(connectionString);
                    _connection.Open();
                }
                if (_connection.State == ConnectionState.Closed)
                {
                    _connection.Open();
                }
                if (_connection.State == ConnectionState.Broken)
                {
                    _connection.Close();
                    _connection.Open();
                }
                return GetConnection._connection;
            }
         
        }
      /// <summary>
      /// 获取表数据
      /// </summary>
      /// <param name="sql"></param>
      /// <returns></returns>
        public static SqlDataReader GetDataRead(string sql)
        {
            SqlCommand command = new SqlCommand(sql, Connection);
            SqlDataReader read = command.ExecuteReader();
            return read;
        }
        public static int NoSelect(string sql)
        {
            SqlCommand command = new SqlCommand(sql, Connection);
            int row = command.ExecuteNonQuery();
            return row;
        }
        public static DataTable GetDataTable(string sql)
        {
            SqlCommand command = new SqlCommand(sql, Connection);
            DataTable dt = new DataTable();
            SqlDataAdapter sda = new SqlDataAdapter(command);
            sda.Fill(dt);
            return dt;
        }

    }
}