ADO.NET無連接模式的詳細介紹

更新時間：2013年10月09日 16:00:38 作者：

這篇文章詳細介紹了ADO.NET無連接模式及操作實例，有需要的朋友可以參考一下

無連接模式：可以在沒有打開連接時在內存中操作數據，DataAdapter通過管理連接為無連接模式提供服務，當要從數據庫中查詢數據時，DataAdapter打開一個連接，填充指定的DataSet,等數據讀取完馬上自動關閉連接，然后可以對數據做修改，再次使用DataAdapter打開連接，持久化修改(無論是更新，刪除或是更新)，最后自動關閉連接，使用無連接模式的情況是有一些獨立數據，它們不會發(fā)生改變或者很少改變，因為在將填充DataSet和更新數據這段時間內數據庫中的實際數據也許會發(fā)生改變，如果需要將數據立即持久化到數據庫請使用連接模式

讀取數據到DataSet:無連接意味著一個連接建立了一個與數據庫的會話，請求的數據讀入到DataSet中，然后通過斷開數據庫的連接關閉會話，這時會話因為與數據庫的斷開而關閉，DataSet成為一個無連接的數據庫

復制代碼代碼如下:

/// <summary>
      /// 查詢學生信息
      /// </summary>
      /// <returns>返回填充了學生表的DataSet</returns>
      public DataSet GetUserInfor()
      {
          string str = "Data Source=.;Initial Catalog=Student;Integrated Security=True";
          var conn = new SqlConnection(str);
          DataSet ds = new DataSet();
          var sda = new SqlDataAdapter("SELECT * FROM Student",conn);
          sda.Fill(ds, "student");//調用fill方法時，SqlDataAdapter會自動打開連接，讀取數據然后關閉連接
          foreach (DataRow dr in ds.Tables["student"].Rows)
          {
              Console.WriteLine(dr["name"]);
          }
          return ds;
      }

將DataSet的修改保存到數據庫
插入數據

復制代碼代碼如下:

/// <summary>
      /// 插入學生信息，并返回插入后的DataSet
      /// </summary>
      /// <param name="stu">學生實體類</param>
      public DataSet InsertStudnt(Student stu)
      {
          DataSet ds = GetUserInfor();
          string str = "Data Source=.;Initial Catalog=Student;Integrated Security=True";
          string sql = "INSERT INTO student VALUES (@name,@age)";
          var conn = new SqlConnection(str);
          var cmd = new SqlCommand(sql,conn);
          var sda = new SqlDataAdapter();
          SqlParameter sqlParam1 = new SqlParameter()
          {
              ParameterName = "@name",
              SourceColumn = "name"
          };
          SqlParameter sqlParam2 = new SqlParameter()
          {
              ParameterName = "@age",
              SourceColumn = "age"
          };
          SqlParameter[] sqlParamArray = new SqlParameter[] {sqlParam1,sqlParam2 };
          cmd.Parameters.AddRange(sqlParamArray);
          sda.InsertCommand = cmd;
          DataRow dr = ds.Tables["student"].NewRow();
          dr["name"] = stu.name;
          dr["age"] = stu.age;
          ds.Tables["student"].Rows.Add(dr);
          sda.Update(ds,"student");
          return ds;

      }

更新數據

復制代碼代碼如下:

/// <summary>
      /// 根據ID更新姓名和年齡
      /// </summary>
      /// <param name="name">姓名</param>
      /// <param name="age">年齡</param>
      /// <param name="id">學生ID</param>
      /// <returns>返回更新后的DataSet</returns>
      public DataSet UpdateStudent(Student stu,int id)
      {
          DataSet ds = GetUserInfor();
          string str = "Data Source=.;Initial Catalog=Student;Integrated Security=True";
          string sql = "UPDATE student SET name=@name,age=@age WHERE id=@id";
          var conn = new SqlConnection(str);
          var cmd = new SqlCommand(sql, conn);
          var sda = new SqlDataAdapter();
          SqlParameter param1 = new SqlParameter()
          {
              ParameterName="@name",SourceColumn="name"
          };
          SqlParameter param2 = new SqlParameter()
          {
              ParameterName = "@age",
              SourceColumn = "age",
              SqlDbType=SqlDbType.Int
          };
          SqlParameter param3 = new SqlParameter()
          {
              ParameterName = "@id",
              SourceColumn = "id"
          };
          SqlParameter[] param = new SqlParameter[] {param1,param2,param3 };
          cmd.Parameters.AddRange(param);
          sda.UpdateCommand = cmd;
          DataTable dt = ds.Tables["student"];
          foreach (DataRow dr in dt.Rows)
          {
              int oldID=Convert.ToInt32(dr["id"]);
              if (oldID == id)
              {
                  dr["name"] = stu.name;
                  dr["age"] = stu.age;
              }
          }
          sda.Update(ds,"student");
          return ds;
      }

刪除數據

復制代碼代碼如下:

/// <summary>
      /// 根據ID刪除一個學生
      /// </summary>
      /// <param name="id">返回更新后的DataSet</param>
      public DataSet DeleteStudent(int id)
      {
          DataSet ds = GetUserInfor();
          string str = "Data Source=.;Initial Catalog=Student;Integrated Security=True";
          string sql = "DELETE FROM student WHERE id=@id";
          var conn = new SqlConnection(str);
          var cmd = new SqlCommand(sql, conn);
          var sda = new SqlDataAdapter();
          SqlParameter param = new SqlParameter()
          {
              ParameterName="@id",SourceColumn="id",SqlDbType=SqlDbType.Int
          };
          cmd.Parameters.Add(param);
          sda.DeleteCommand = cmd;
          DataTable dt=ds.Tables["student"];
          foreach (DataRow dr in dt.Rows)
          {
              int oldId = Convert.ToInt32(dr["id"]);
              if (oldId == id)
                  dr.Delete();
          }
          sda.Update(ds,"student");
          return ds;
      }