Question

I have been heavily contemplating adding the Embedded MYSQL Server Library into my application. My software is a layer between a Game Server and a Web Management Panel that provides extra functionality. Many of our customers have been requesting MySQL databases for their servers (since this is what their plugins are developed to use), and being able to run one within my software rather than manually set them up would be fantastic.

• Is there a .NET wrapper for this library I am missing?

• The software being ran by my application will need to be able to connect to it, but the software is obviously being ran locally. Will this work?

Answer 1

i’m not aware of any .NET wrapper for this library although i remember there was a talk about introducing support for this library in the .NET Connector from version 5. I can’t find any information about that right now though.

There is some sample code out there on the web which you can extend your code upon. I quess the most complete would be http://forums.mysql.com/read.php?38,67281,67917 ->

using System;
using System.Runtime.InteropServices;
using System.Diagnostics;
using System.Configuration;

class EntryPoint
{
    [DllImport("libmySQL.dll")]
    static extern IntPtr mysql_init(IntPtr mysql);

    [DllImport("libmySQL.dll")]
    static extern IntPtr mysql_fetch_lengths(IntPtr result);

    [DllImport("libmySQL.dll")]
    static extern IntPtr mysql_store_result(IntPtr mysql);

    [DllImport("libmySQL.dll")]
    static extern IntPtr mysql_fetch_row(IntPtr result);

    [DllImport("libmySQL.dll")]
    static extern IntPtr mysql_real_connect(IntPtr mysql, string host, string user, string passwd, string db, uint port, string unix_socket, uint client_flag);

    [DllImport("libmySQL.dll")]
    static extern uint mysql_field_count(IntPtr mysql);

    [DllImport("libmySQL.dll")]
    static extern string mysql_error(IntPtr mysql);

    [DllImport("libmySQL.dll")]
    static extern int mysql_real_query(IntPtr mysql, string query, uint length);

    static Array MarshalArray(Type structureType, IntPtr arrayPtr, int length)
    {
        if (structureType == null)
            throw new ArgumentNullException("structureType");
        if (!structureType.IsValueType)
            throw new ArgumentException("Only struct types are supported.", "structureType");
        if (length < 0)
            throw new ArgumentOutOfRangeException("length", length, "length must be equal to or greater than zero.");
        if (arrayPtr == IntPtr.Zero)
            return null;
        int size = System.Runtime.InteropServices.Marshal.SizeOf(structureType);
        Array array = Array.CreateInstance(structureType, length);
        for (int i = 0; i < length; i++)
        {
            IntPtr offset = new IntPtr((long)arrayPtr + (size * i));
            object value = System.Runtime.InteropServices.Marshal.PtrToStructure(offset, structureType);
            array.SetValue(value, i);
        }
        return array;
    }


    static void mysql_real_query(IntPtr mysql, string query)
    {
        int result = (query != null) ? mysql_real_query(mysql, query, (uint)query.Length) : mysql_real_query(mysql, null, 0);
        if (result == 0)
            return;
        throw new ApplicationException(mysql_error(mysql));
    }

    static int Main(string[] args)
    {
        IntPtr ptr = mysql_init(IntPtr.Zero);
        Debug.Assert(ptr != IntPtr.Zero);

        IntPtr mysql = mysql_real_connect(ptr, ConfigurationSettings.AppSettings["server"], ConfigurationSettings.AppSettings["username"], ConfigurationSettings.AppSettings["password"], ConfigurationSettings.AppSettings["database"], 0, null, 0);
        Debug.Assert(ptr != IntPtr.Zero, mysql_error(ptr));

        string query = "SELECT * FROM proxy_servers";
        Console.WriteLine("Executing query: {0}", query);
        mysql_real_query(mysql, query);

        IntPtr result = mysql_store_result(mysql);
        Debug.Assert(result != IntPtr.Zero, mysql_error(mysql));

        uint fieldCount = mysql_field_count(mysql);
        Console.WriteLine("field count: {0}", fieldCount);

        for (IntPtr ptrRow = mysql_fetch_row(result); ptrRow != IntPtr.Zero; ptrRow = mysql_fetch_row(result))
        {
            IntPtr[] mysqlRow = (IntPtr[])MarshalArray(typeof(IntPtr), ptrRow, (int)fieldCount);
            IntPtr ptrLengths = mysql_fetch_lengths(result);
            uint[] lengths = (uint[])MarshalArray(typeof(uint), ptrLengths, (int)fieldCount);
            for (int i = 0; i < (int)fieldCount; i++)
            {
                string str = Marshal.PtrToStringAnsi(mysqlRow[i], (int)lengths[i]);
                Console.Write("{0}, ", str);
            }
            Console.WriteLine();
        }
        return 0;
    }
}