我开发了C＃应用程序，我在程序中关闭了读取器，cekprevnext中的读者是错误的，它说＆＃34;无效的尝试读取，当读取器关闭时＃34;，所以这就是我的所有代码：
private void cekprevnext()
{
ambilsoal();
con.Open();
MySqlCommand cmds = new MySqlCommand("Select * from jawab_soal WHere SoalID='"+SOALID+"'", con);
MySqlDataReader drs = cmds.ExecuteReader();
if (drs.HasRows)
{
while (drs.Read()) // ==> This attempt reader close
{
jwbsudah = drs["jambilsoal"].ToString();
if (jwbA.Text == jwbsudah)
{
jwbA.Checked = true;
}
else if (jwbB.Text == jwbsudah)
{
jwbB.Checked = true;
}
else if (jwbC.Text == jwbsudah)
{
jwbC.Checked = true;
}
else
{
jwbD.Checked = true;
}
}
}
con.Close();
}
这是我的ambil soal方法：
private void ambilsoal()
{
jwbA.Checked = false;
jwbB.Checked = false;
jwbC.Checked = false;
jwbD.Checked = false;
if (count == jml)
{
btnnext.Enabled = false;
btnprev.Enabled = true;
}
else if (count == 1)
{
btnprev.Enabled = false;
btnnext.Enabled = true;
}
else
{
btnnext.Enabled = true;
btnprev.Enabled = true;
}
try
{
con.Open();
MySqlCommand cmd = new MySqlCommand("SELECT * From soal Where KatID='" + KatID + "' AND NoSoal='"+count+"'", con);
MySqlDataReader dr = cmd.ExecuteReader();
while (dr.Read())
{
soalTampil.Text = dr["Pertanyaan"].ToString();
jwbA.Text = dr["A"].ToString();
jwbB.Text = dr["B"].ToString();
jwbC.Text = dr["C"].ToString();
jwbD.Text = dr["D"].ToString();
SOALID = dr["SoalID"].ToString();
jwbbelum = dr["Jawaban"].ToString();
}
con.Close();
}
catch (Exception ex)
{
con.Close();
RadMessageBox.Show(ex.Message.ToString());
}
}