#region LICENSE
/*
MySQLDriverCS: An C# driver for MySQL.
Copyright (c) 2002 Manuel Lucas Vi襻s Livschitz.

This file is part of MySQLDriverCS.

MySQLDriverCS is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.

MySQLDriverCS is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with MySQLDriverCS; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#endregion
using System;
using System.Data;
using System.Runtime.InteropServices;
namespace MySQLDriverCS
{
//[StructLayout(LayoutKind.Sequential)]
public class MYSQL_FIELD_FACTORY
{
static string version;
public static IMYSQL_FIELD GetInstance()
{

if (version==null)
{
version = CPrototypes.GetClientInfo();
}
if (version.CompareTo("4.1.2-alpha")>=0)
{
return new MYSQL_FIELD_VERSION_5();
}
else
return new MYSQL_FIELD_VERSION_3();
}
}
public interface IMYSQL_FIELD
{
string Name{get;}
uint Type{get;}
long Max_Length {get;}
}
///

/// Field descriptor
///

[StructLayout(LayoutKind.Sequential)]//"3.23.32", 4.0.1-alpha
internal class MYSQL_FIELD_VERSION_3: IMYSQL_FIELD
{
///

/// Name of column
///

public string name;
///

/// Table of column if column was a field
///

public string table;
//public string org_table; /* Org table name if table was an alias */
//public string db; /* Database for table */
///

/// def
///

public string def;
///

/// length
///

public long length;
///

/// max_length
///

public long max_length;
///

/// Div flags
///

public uint flags;
///

/// Number of decimals in field
///

public uint decimals;
///

/// Type of field. Se mysql_com.h for types
///

public uint type;

///

/// Name
///

public string Name
{
get{return name;}
}
///

/// Type
///

public uint Type
{
get{return type;}
}
///

/// Max_Length
///

public long Max_Length
{
get {return max_length;}
}
}

///

/// Field descriptor
///

[StructLayout(LayoutKind.Sequential)]
internal class MYSQL_FIELD_VERSION_5: IMYSQL_FIELD
{
///

/// Name of column
///

public string name;
///

/// Original column name, if an alias
///

public string org_name;
///

/// Table of column if column was a field
///

public string table;
///

/// Org table name if table was an alias
///

public string org_table;
///

/// Database for table
///

public string db;
///

/// Catalog for table
///

//public string catalog;
///

/// def
///

public string def;
///

/// length
///

public long length;
///

/// max_length
///

public long max_length;
///

/// name_length
///

//public uint name_length;
///

/// org_name_length
///

public uint org_name_length;
///

/// table_length
///

public uint table_length;
///

/// org_table_length
///

public uint org_table_length;
///

/// db_length
///

public uint db_length;
///

/// catalog_length
///

public uint catalog_length;
///

/// def_length
///

public uint def_length;
///

/// Div flags
///

public uint flags;
///

/// Number of decimals in field
///

public uint decimals;
///

/// Character set
///

public uint charsetnr;
///

/// Type of field. Se mysql_com.h for types
///

public uint type;

///

/// Name
///

public string Name
{
get {return name;}
}
///

/// Type
///

public uint Type
{
get {return type;}
}
///

/// Max_Length
///

public long Max_Length
{
get {return max_length;}
}
}

//[StructLayout(LayoutKind.Explicit)]
public enum enum_field_types
{
FIELD_TYPE_DECIMAL, FIELD_TYPE_TINY,
FIELD_TYPE_SHORT, FIELD_TYPE_LONG,
FIELD_TYPE_FLOAT, FIELD_TYPE_DOUBLE,
FIELD_TYPE_NULL, FIELD_TYPE_TIMESTAMP,
FIELD_TYPE_LONGLONG,FIELD_TYPE_INT24,
FIELD_TYPE_DATE, FIELD_TYPE_TIME,
FIELD_TYPE_DATETIME, FIELD_TYPE_YEAR,
FIELD_TYPE_NEWDATE,
FIELD_TYPE_ENUM=247,
FIELD_TYPE_SET=248,
FIELD_TYPE_TINY_BLOB=249,
FIELD_TYPE_MEDIUM_BLOB=250,
FIELD_TYPE_LONG_BLOB=251,
FIELD_TYPE_BLOB=252,
FIELD_TYPE_VAR_STRING=253,
FIELD_TYPE_STRING=254,
FIELD_TYPE_GEOMETRY=255

};

///

/// C prototypes warpper for mysqllib.
///

internal class CPrototypes
{
[ DllImport( "libmySQL.dll", EntryPoint="mysql_init" )]
unsafe public static extern void* mysql_init(void* must_be_null);
[ DllImport( "libmySQL.dll", EntryPoint="mysql_close" )]
unsafe public static extern void mysql_close(void* handle);

// BEGIN ADDITION 2004-07-01 BY Alex Seewald
// Enables us to call mysql_option to activate compression and timeout
[ DllImport( "libmySQL.dll", EntryPoint="mysql_options" )]
unsafe public static extern void mysql_options(void* mysql, uint option, uint *value);
// END ADDITION 2004-07-01 By Alex Seewald


[ DllImport( "libmySQL.dll", EntryPoint="mysql_real_connect" )]
unsafe public static extern void* mysql_real_connect(void* mysql, string host, string user, string passwd, string db, uint port, string unix_socket, int client_flag);
[ DllImport( "libmySQL.dll", EntryPoint="mysql_query" )]
unsafe public static extern int mysql_query(void*mysql, string query);
[ DllImport( "libmySQL.dll", EntryPoint="mysql_store_result" )]
unsafe public static extern void *mysql_store_result(void *mysql);
[ DllImport( "libmySQL.dll", EntryPoint="mysql_free_result" )]
unsafe public static extern void mysql_free_result(void*result);
[ DllImport( "libmySQL.dll", EntryPoint="mysql_errno" )]
unsafe public static extern uint mysql_errno(void*mysql);
[ DllImport( "libmySQL.dll", EntryPoint="mysql_error" )]
unsafe public static extern string mysql_error(void*mysql);
[ DllImport( "libmySQL.dll", EntryPoint="mysql_field_count" )]
unsafe public static extern uint mysql_field_count(void*mysql);
[ DllImport( "libmySQL.dll", EntryPoint="mysql_affected_rows" )]
unsafe public static extern ulong mysql_affected_rows(void*mysql);
[ DllImport( "libmySQL.dll", EntryPoint="mysql_num_fields" )]
unsafe public static extern uint mysql_num_fields(void*result);
[ DllImport( "libmySQL.dll", EntryPoint="mysql_num_rows" )]
unsafe public static extern ulong mysql_num_rows(void *result);
[ DllImport( "libmySQL.dll", EntryPoint="mysql_fetch_field_direct" )]
unsafe public static extern IntPtr mysql_fetch_field_direct(void*result, uint fieldnr);

///Returns a string that represents the client library version
[DllImport("libmySQL.dll",CharSet=System.Runtime.InteropServices.CharSet.Ansi,
EntryPoint="mysql_get_client_info", ExactSpelling=true)]
public static extern string GetClientInfo();

[ DllImport( "libmySQL.dll", EntryPoint="mysql_fetch_row" )]
unsafe public static extern IntPtr mysql_fetch_row(void*result);
[ DllImport( "libmySQL.dll", EntryPoint="mysql_select_db" )]
unsafe public static extern int mysql_select_db(void*mysql,string dbname);
[ DllImport( "libmySQL.dll", EntryPoint="mysql_fetch_lengths" )]
unsafe public static extern UInt32 *mysql_fetch_lengths(void*result);

}
}

　　基本上是将C风格的基础数据结构进行.net的重新定义，然后通过InteropServices进行访问。

　　具体如何利用这个库进行操作，可以参考其中的例子。