#45 Transactions broken for DB read

[Anonymous]

Selecting data from the DB while inside a transaction
returns:

Exception: System.NullReferenceException
Message: Object reference not set to an instance of an
object.
Source: ByteFX.Data
at
ByteFX.Data.MySqlClient.MySqlDataReader.GetValue(Int32
i) in
Z:\workingcopy\mysqldriver\MySqlClient\datareader.cs:line
35
at
ByteFX.Data.MySqlClient.MySqlDataReader.GetInt32(Int32
i) in
Z:\workingcopy\mysqldriver\MySqlClient\datareader.cs:line
476
at .... (my code)

The problems seems to originate in the
MySqlClient/Driver.cs class in 'ReadPacket()' where the
packet type is returned as UpdateOrOk, which causes
problems around line 152 of MySqlClient/datareader.cs

[Reggie Burnett]

Logged In: YES
user_id=523261

Do you have a code snippet you can send me that shows the
problem?

Thanks
Reggie

[Nobody/Anonymous]

Logged In: NO

Using MySql for windows version 4.0.13-nt on WinXP pro,
ByteFx driver version 0.7.0.34801, the following code breaks
with the given SQL.

--
-- SQL
--
CREATE TABLE account (
id INTEGER PRIMARY KEY,
balance INTEGER NOT NULL
);

INSERT INTO account VALUES(1, 100);

using System;
using ByteFX.Data.MySqlClient;

namespace MySqlTest
{
class Test1
{
public Test1()
{
int id = 1;
int extra = 200;

        string connectionString = "server=localhost;user

id=root;database=test";
MySqlConnection connection = new
MySqlConnection(connectionString);
connection.Open();

        MySqlTransaction transaction = connection.BeginTransaction\(\);

        MySqlParameter idParam = new MySqlParameter\("@id",

MySqlDbType.Int24, "id");
idParam.Value = id;

        string sql = "SELECT balance FROM account WHERE id = @id";            
        MySqlCommand cmd = new MySqlCommand\(sql, connection,

transaction);
cmd.Parameters.Add(idParam);
MySqlDataReader reader = cmd.ExecuteReader();

        while \(reader.Read\(\)\) 
        \{
            int balance = reader.GetInt32\(0\);
            reader.Close\(\);

            MySqlParameter balanceParam = new

MySqlParameter("@balance", MySqlDbType.Int24, "balance");
balanceParam.Value = balance + extra;
idParam.Value = id;

            sql = "UPDATE account SET balance = @balance WHERE id =

@id";
cmd = new MySqlCommand(sql, connection, transaction);
cmd.Parameters.Add(idParam);
cmd.Parameters.Add(balanceParam);

            int updateCount = cmd.ExecuteNonQuery\(\);              
            if \(updateCount == 1\) 
            \{
                transaction.Commit\(\);
                connection.Close\(\);
                return;
            \} 
            else 
            \{
                transaction.Rollback\(\);
                connection.Close\(\);
                return;
            \}
        \}

        reader.Close\(\);
        transaction.Rollback\(\);
        connection.Close\(\);
    \}

    \[STAThread\]
    static void Main\(string\[\] args\)
    \{
        new Test1\(\);
    \}
\}

}