从数据库获取数据

  //从数据库获取数据
  public static DataTable GetData0()
      {
          SqlConnection sqlcon = new SqlConnection();
          sqlcon.ConnectionString = "Catalog=JinKeLi;Data Source=(local);uid=sa;pwd=123";
          if(sqlcon.State == ConnectionState.Closed)
          {
              sqlcon.Open();
          }
          //接下来初始化命令
          SqlCommand cmd = new SqlCommand();
          cmd.Connection = sqlcon;
          cmd.CommandType = CommandType.Text;
          cmd.CommandText = "select * from Tb_Config";
          //用于执行数据的插入，更新，删除的操作；返回被影响的行数
          int i = cmd.ExecuteNonQuery();
          if(i > 0)
          {
              Console.WriteLine("<script>alert('操作成功')</script>");
          }
          //用于查询最大值只需返回一条数据情况下的操作，返回的是首行第一行的数据
          object obj = cmd.ExecuteScalar();
          DataSet ds = new DataSet();
          DataTable dt = new DataTable();
          SqlDataAdapter sda = new SqlDataAdapter();
          sda.SelectCommand = cmd; //SelectCommand用于获取cmd命令的执行的操作
          sda.Fill(dt);
          return dt;
      }
      //若要创建 SqlDataReader，必须调用 SqlCommand 对象的 ExecuteReader 方法，
      //而不要直接使用构造函数
  public static void GetData1()
  {
      string str = "Data Source=.;Initial Catalog=JinLeLi;Initial Security=true;";
      string sql = "select * from Tb_Config";
      SqlConnection conn = new SqlConnection();
      conn.Open();
      SqlCommand comm = new SqlCommand(sql, conn);
      DataSet ds = new DataSet();
      SqlDataReader dr = comm.ExecuteReader();
      if(dr.Read())
      {
          //下面的俩中方法都可以获取数据
          //根据序列
          this.TextBox1.Text = dr.GetString(1);
          this.TextBox2.Text = dr.GetString(2);
          //根据字段
          this.TextBox1.Text = dr.GetString(dr.GetOrdinal("Name"));
          this.TextBox2.Text = dr.GetInt32(dr.GetOrdinal("Age").ToString());
      }
      //用到SQLDataReader要用循环输出
      while(dr.Read())
      {
          Console.WriteLine(dr["Name"]);
          Console.WriteLine(dr["Age"]);
      }
      dr.Close();
      if(conn.State == ConnectionState.Open)
      {
          conn.Close();
      }
  }