显示以下代码...给定已经有一个与此Connection关联的打开DataReader，必须先关闭它。呃请帮忙 [英] show the following code... its given There is already an open DataReader associated with this Connection which must be closed first. errer please help

问题描述

private void forselectquery()
        {
            MySqlConnection con = new MySqlConnection("Server=xxxxxxxxxx; UserId=xxxxxxxx; Password=xxxxxxxx; Database=xxxxxxxxx;");

            con.Open();
            MySqlDataAdapter da = new MySqlDataAdapter();
       

            for (int i = 0; i < dataGridView1.Rows.Count; i++)
            {
                try
                {
                   
                   

                    String str1 = "select * from UrlReport where URL=@URL and Title=@Title and LastVisited=@LastVisited and Date=@Date";
                    MySqlCommand cmd1 = new MySqlCommand(str1, con);
                   

                    cmd1.Parameters.AddWithValue("@URL", dataGridView1.Rows[i].Cells[0].Value);
                    cmd1.Parameters.AddWithValue("@Title", dataGridView1.Rows[i].Cells[1].Value);
                    cmd1.Parameters.AddWithValue("@LastVisited", dataGridView1.Rows[i].Cells[2].Value);
                    cmd1.Parameters.AddWithValue("@Date", label3.Text);
                    MySqlDataReader DR1 = cmd1.ExecuteReader();
                    if (DR1.Read())
                    {
                        MessageBox.Show("google"); 
                    }
                    else
                    {



                        String str = "INSERT INTO UrlReport(Date,MacAddress,URL,Title,LastVisited,LastUpdated,Expires) VALUES (@Date,@MacAddress,@URL,@Title,@LastVisited,@LastUpdated,@Expires)";
                        MySqlCommand cmd = new MySqlCommand(str, con);
                        cmd.Parameters.AddWithValue("@Date", label3.Text);
                        cmd.Parameters.AddWithValue("@MacAddress", lblMacAddress.Text);
                        cmd.Parameters.AddWithValue("@URL", dataGridView1.Rows[i].Cells[0].Value);
                        cmd.Parameters.AddWithValue("@Title", dataGridView1.Rows[i].Cells[1].Value);
                        cmd.Parameters.AddWithValue("@LastVisited", dataGridView1.Rows[i].Cells[2].Value);
                        cmd.Parameters.AddWithValue("@LastUpdated", dataGridView1.Rows[i].Cells[3].Value);
                        cmd.Parameters.AddWithValue("@Expires", dataGridView1.Rows[i].Cells[4].Value);
                        da.InsertCommand = cmd;
                        cmd.ExecuteNonQuery();
                        con.Close();
                       

                    }

                    DR1.Close();
                }
                catch (Exception EX)
                {
                   
                    MessageBox.Show("" + EX);
                }
                
            }
           
        

        }

显示以下代码...给定已经有一个与此Connection关联的开放DataReader，必须先关闭它。 errer请帮助

show the following code... its given There is already an open DataReader associated with this Connection which must be closed first. errer please help

推荐答案

在执行另一个查询之前关闭 SqlDataReader

试试这个：

Close the SqlDataReader before executing another query
Try this:

private void forselectquery()
{
MySqlConnection con = new MySqlConnection("Server=xxxxxxxxxx; UserId=xxxxxxxx; Password=xxxxxxxx; Database=xxxxxxxxx;");
 
con.Open();
MySqlDataAdapter da = new MySqlDataAdapter();

 
for (int i = 0; i < dataGridView1.Rows.Count; i++)
{
try
{


 
String str1 = "select * from UrlReport where URL=@URL and Title=@Title and LastVisited=@LastVisited and Date=@Date";
MySqlCommand cmd1 = new MySqlCommand(str1, con);

 
cmd1.Parameters.AddWithValue("@URL", dataGridView1.Rows[i].Cells[0].Value);
cmd1.Parameters.AddWithValue("@Title", dataGridView1.Rows[i].Cells[1].Value);
cmd1.Parameters.AddWithValue("@LastVisited", dataGridView1.Rows[i].Cells[2].Value);
cmd1.Parameters.AddWithValue("@Date", label3.Text);
MySqlDataReader DR1 = cmd1.ExecuteReader();
if (DR1.Read())
{
MessageBox.Show("google");

DR1.Close();//close datareader<--------------------------------
}
else
{
 
DR1.Close();//close datareader<--------------------------------
 
String str = "INSERT INTO UrlReport(Date,MacAddress,URL,Title,LastVisited,LastUpdated,Expires) VALUES (@Date,@MacAddress,@URL,@Title,@LastVisited,@LastUpdated,@Expires)";
MySqlCommand cmd = new MySqlCommand(str, con);
cmd.Parameters.AddWithValue("@Date", label3.Text);
cmd.Parameters.AddWithValue("@MacAddress", lblMacAddress.Text);
cmd.Parameters.AddWithValue("@URL", dataGridView1.Rows[i].Cells[0].Value);
cmd.Parameters.AddWithValue("@Title", dataGridView1.Rows[i].Cells[1].Value);
cmd.Parameters.AddWithValue("@LastVisited", dataGridView1.Rows[i].Cells[2].Value);
cmd.Parameters.AddWithValue("@LastUpdated", dataGridView1.Rows[i].Cells[3].Value);
cmd.Parameters.AddWithValue("@Expires", dataGridView1.Rows[i].Cells[4].Value);
da.InsertCommand = cmd;
cmd.ExecuteNonQuery();
con.Close();

 
}
 
DR1.Close();
}
catch (Exception EX)
{

MessageBox.Show("" + EX);
}

}


 
}

Refer ：已经有了-an-open-datareader-related-with-this-connectio [ ^ ]

Refer: there-is-already-an-open-datareader-associated-with-this-connectio[^]

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