Why Am I Getting \'There is already an open DataReader associated with this Connection which must be closed first\'?

Troubleshooting "There is already an open DataReader associated with this Connection which must be closed first"

In your code, you're attempting to execute another SQL statement ("Insert Into tblProduct_temp") while a data reader is still open, leading to the exception: "There is already an open DataReader associated with this Connection which must be closed first."

Reason:

MySQL connections maintain an exclusive lock on the connection resource when a data reader is open. This prevents other operations from accessing the connection until the data reader is closed.

Solution:

To resolve this issue, you must close the data reader before executing the new SQL statement. The recommended way to do this is to use a using statement or a try-finally block to ensure that the reader is closed properly, even if an exception occurs.

Here's the revised code using a using statement:

using (MySqlConnection myConnection = new MySqlConnection(cf.GetConnectionString()))
{
    myConnection.Open();

    using (MySqlCommand myCommand = new MySqlCommand(SQL, myConnection))
    {
        using (MySqlDataReader myReader = myCommand.ExecuteReader())
        {
            if (myReader.HasRows)
            {
                int i = 0;
                while (myReader.Read())
                {
                    if (myReader["frProductid"].ToString() == "")
                    {
                        strInsertSQL = "Insert Into tblProduct_temp (Productid) Values('this istest') ";
                        using (MySqlCommand cmdInserttblProductFrance = new MySqlCommand(strInsertSQL, myConnection))
                        {
                            cmdInserttblProductFrance.ExecuteNonQuery();
                        }
                    }
                }
            }
        }
    }
}

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