已有打开的与此命令相关联的 DataReader，必须首先将它关闭

Question

请问我这个怎么解决啊？下面是我的代码
string sqlstr = "select [Tip],[Tdate] from tongji where [Tip]='" + serverip + "' and [Tdd]='" + dd + "'";
        System.Data.SqlClient.SqlCommand cmd = new System.Data.SqlClient.SqlCommand(sqlstr, con);
        try
        {
            con.Open();
            System.Data.SqlClient.SqlDataReader reader;
            reader = cmd.ExecuteReader();
            if (reader.Read())
            {            }
            else
            {
                System.Data.SqlClient.SqlCommand cmd2 = new System.Data.SqlClient.SqlCommand("insert into tongji (Tip,Tdate,Thh,Tmm,Tadd,Tdd,TY) values (@Tip,@Tdate,@Thh,@Tmm,@Tadd,@Tdd,@TY)", con);
                cmd2.Parameters.Add(new System.Data.SqlClient.SqlParameter("@Tip", System.Data.SqlDbType.VarChar, 20));
                cmd2.Parameters["@Tip"].Value = serverip;
                cmd2.Parameters.Add(new System.Data.SqlClient.SqlParameter("@Tdate", System.Data.SqlDbType.VarChar, 20));
                cmd2.Parameters["@Tdate"].Value = time;
                cmd2.Parameters.Add(new System.Data.SqlClient.SqlParameter("@Thh", System.Data.SqlDbType.VarChar, 20));
                cmd2.Parameters["@Thh"].Value = hh;
                cmd2.Parameters.Add(new System.Data.SqlClient.SqlParameter("@Tmm", System.Data.SqlDbType.VarChar, 20));
                cmd2.Parameters["@Tmm"].Value = mm;
                cmd2.Parameters.Add(new System.Data.SqlClient.SqlParameter("@Tadd", System.Data.SqlDbType.VarChar, 100));
                cmd2.Parameters["@Tadd"].Value = add;
                cmd2.Parameters.Add(new System.Data.SqlClient.SqlParameter("@Tdd", System.Data.SqlDbType.VarChar, 100));
                cmd2.Parameters["@Tdd"].Value = dd;
                cmd2.Parameters.Add(new System.Data.SqlClient.SqlParameter("@TY", System.Data.SqlDbType.VarChar, 100));
                cmd2.Parameters["@TY"].Value = yy;
                cmd2.ExecuteNonQuery();
                reader.Close();
            }
        }
        catch (Exception ex)
        {
            throw (ex);
        }
        finally
        {
            con.Close();
        }

Answer 1

使用DataReader没有关闭前，不能再调用数据库。你把DataReader换成别的就可以了

Answer 2

    finally 
        { 
            con.Close(); 
        } 
 
` `   用泛型集合做吧·

Answer 3

已有打开的与此命令相关联的 DataReader，必须首先将它关闭  

Answer 4

reader = cmd.ExecuteReader();
            if (reader.Read())
            {              // 完成你应该完成的功能
              reader.Close();
            }
            else
            {
                reader.Close();
                System.Data.SqlClient.SqlCommand cmd2 = new System.Data.SqlClient.SqlCommand("insert into tongji (Tip,Tdate,Thh,Tmm,Tadd,Tdd,TY) values (@Tip,@Tdate,@Thh,@Tmm,@Tadd,@Tdd,@TY)", con);
                cmd2.Parameters.Add(new System.Data.SqlClient.SqlParameter("@Tip", System.Data.SqlDbType.VarChar, 20));
                cmd2.Parameters["@Tip"].Value = serverip;
                cmd2.Parameters.Add(new System.Data.SqlClient.SqlParameter("@Tdate", System.Data.SqlDbType.VarChar, 20));
                cmd2.Parameters["@Tdate"].Value = time;
                cmd2.Parameters.Add(new System.Data.SqlClient.SqlParameter("@Thh", System.Data.SqlDbType.VarChar, 20));
                cmd2.Parameters["@Thh"].Value = hh;
                cmd2.Parameters.Add(new System.Data.SqlClient.SqlParameter("@Tmm", System.Data.SqlDbType.VarChar, 20));
                cmd2.Parameters["@Tmm"].Value = mm;
                cmd2.Parameters.Add(new System.Data.SqlClient.SqlParameter("@Tadd", System.Data.SqlDbType.VarChar, 100));
                cmd2.Parameters["@Tadd"].Value = add;
                cmd2.Parameters.Add(new System.Data.SqlClient.SqlParameter("@Tdd", System.Data.SqlDbType.VarChar, 100));
                cmd2.Parameters["@Tdd"].Value = dd;
                cmd2.Parameters.Add(new System.Data.SqlClient.SqlParameter("@TY", System.Data.SqlDbType.VarChar, 100));
                cmd2.Parameters["@TY"].Value = yy;
                cmd2.ExecuteNonQuery();
                reader.Close();
            }