Question

This function will display an error that “connection has not been properly initialized.” Why?

public void updateCustomer()
{
     using (SqlCeConnection aConnection = new SqlCeConnection(@"Data Source=|DataDirectory|\Database.sdf"))
     {
            aConnection.Open();
            using (SqlCeCommand aCommand = new SqlCeCommand("UPDATE customer SET credit = @credit WHERE(ID = @ID)"))
            {
                aCommand.Parameters.Add(new SqlCeParameter("credit", SqlDbType.NVarChar, 100)).Value = getRemaining();
                aCommand.Parameters.Add(new SqlCeParameter("ID", SqlDbType.Int, 8)).Value = Convert.ToInt32(textBox2.Text);

                int resultUpdate = aCommand.ExecuteNonQuery();
                if (resultUpdate != -1)
                    label9.Text = "customer updated sussessfully";
                else
                    label9.Text = "some error in updating customer";
                aConnection.Close();
            }
     }
}

Answer 1

you need to set the connection for the SqlCeCommand

SqlCeCommand command = new SqlCeCommand(
    queryString, connection);

set connection string as

@"Data Source=|DataDirectory|\Database.sdf;Persist Security Info=False;"

check Connection strings for SQL Server Compact Edition for more information