Fix Linq 2 NHibernate for MySQL

If you use NHibernate with MySQL and Linq 2 NHibernate to simplify fetching data you may face with problem: queries created by Linq2NH use square brackets by default. That is fine for SQL Server but won't work in MySQL which uses backticks ``.

For MySQL we need to instruct NHibernate to use backticks instead of square brackets. It can be done by setting interceptor in NH config:

public class NHConfiguration
{
    public static Configuration Build(string connStr)
    {
        var config = Fluently.Configure()
            .Database(
                MySQLConfiguration.Standard
                    .ConnectionString(connStr)
                    .AdoNetBatchSize(100)
                    .DoNot.ShowSql()
            )
            .Mappings(cfg =>
            {
                // add mappings
            })
            .ExposeConfiguration(x =>
            {
with backticks for MySQL
                x.SetInterceptor(new ReplaceBracesWithBackticksInterceptor());
            });

        return config.BuildConfiguration();
    }
}

in its OnPrepareStatement method we just replace square brackets with backticks:

public class ReplaceBracesWithBackticksInterceptor : EmptyInterceptor
{
    public override NHibernate.SqlCommand.SqlString OnPrepareStatement(NHibernate.SqlCommand.SqlString sql)
    {
        return sql.Replace("[", "`").Replace("]", "`");
    }
}

After that Linq2NH will start working in MySQL.