How to Resolve the \'There is already an open DataReader...\' SQL Exception?

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

This exception occurs when a DataReader is still open while attempting to execute another SQL command on the same connection. Here's how to resolve the issue based on the given code:

In your code, you open a DataReader using the ExecuteReader() method and then attempt to execute another command using ExecuteNonQuery(). This is not allowed because the DataReader holds a lock on the connection. To resolve this issue, close the DataReader before executing any additional commands.

SQL = "Select * from tblProduct";

//Create Connection/Command/MySQLDataReader
MySqlConnection myConnection = new MySqlConnection(cf.GetConnectionString());
myConnection.Open();
MySqlCommand myCommand = new MySqlCommand(SQL, myConnection);
MySqlDataReader myReader = myCommand.ExecuteReader();
myCommand.Dispose();

if (myReader.HasRows)
{
    int i = 0;
    // Always call Read before accessing data.
    while (myReader.Read())
    {
        if (myReader["frProductid"].ToString() == "") //there is no productid exist for this item
        {
            strInsertSQL = "Insert Into tblProduct_temp (Productid) Values('this istest') ";
            MySqlCommand cmdInserttblProductFrance = new MySqlCommand(strInsertSQL, myConnection);
            
            // Close the DataReader before executing the new command
            myReader.Close();
            
            cmdInserttblProductFrance.ExecuteNonQuery(); // Now this will execute successfully
        }
    }
}

After closing the DataReader, you can execute the cmdInserttblProductFrance command without encountering the "There is already an open DataReader associated with this Connection which must be closed first" exception.

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