Counting rows in mysql table through procedure and interface in c#

I'm trying to build a script for a Grand Theft Auto V modification. It's essentially a drug dealer job for online role play servers.

I have the following interface:

namespace DrugDealer
{
    public interface IDrugDealerJobRepository
    {
        DrugDealerJob GetJob(int jobId);
        int CountJobs();
    }
}

I have the following class:

namespace DrugDealer
{
    public class DrugDealerJob
    {
        public int JobId { get; set; }
        public string Drug { get; set; }
        public int UnitBuyPrice { get; set; }
        public int UnitSalePrice { get; set; }
        public string Location { get; set; }
        public string Vehicle { get; set; }
        public string VehicleHash { get; set; }
        public float X { get; set; }
        public float Y { get; set; }
        public float Z { get; set; }
    }
}

I have the following class which acts as main:

using System;
using System.Collections.Generic;
using GTANetworkServer;
using Insight.Database;
using Insight.Database.Providers.MySql;
using MySql.Data.MySqlClient;
using Database;
using System.Threading;

namespace DrugDealer
{
    public class Main : Script
    {
        private static MySqlConnectionStringBuilder _database;
        private IUserRepository _userRepository;
        private IDrugDealerJobRepository _drugDealerJobRepository;

        public Main()
        {
            API.onResourceStart += API_onResourceStart;
        }

        private void API_onResourceStart()
        {
            API.consoleOutput("Starting DrugDealer!");

            MySqlInsightDbProvider.RegisterProvider();
            _database = new MySqlConnectionStringBuilder("");
            _userRepository = _database.Connection().As<IUserRepository>();
            _drugDealerJobRepository = _database.Connection().As<IDrugDealerJobRepository>();

            ThreadStart drugDealerJob = new ThreadStart(StartDrugDealerJob);
            Console.WriteLine("[" + DateTime.Now.ToLongTimeString() + "] Creating the drug dealer job thread");
            Thread dealerJob = new Thread(drugDealerJob);
            dealerJob.Start();
        }

        public void StartDrugDealerJob()
        {
            Console.WriteLine("[" + DateTime.Now.ToLongTimeString() + "] Dealer Job Starts thread");

            // keep checking until players are on the server
            PlayersOnServer();

            int sleepfor = 5000; // 3600000 in one hour which we be using later
            int i = 10;
            while (i != 0)
            {
                List<Client> players = API.getAllPlayers();
                foreach(Client player in players)
                {
                    int numberOfJobs = _drugDealerJobRepository.CountJobs();
                    Console.WriteLine("[" + DateTime.Now.ToLongTimeString() + "] Number of Jobs:  {0}", numberOfJobs);
                    DrugDealerJob currentJob = _drugDealerJobRepository.GetJob(new Random().Next(1, numberOfJobs));
                    Console.WriteLine("[" + DateTime.Now.ToLongTimeString() + "] A Drug Shipment of {0} has arrived at {1}. Look out for a {2}", currentJob.Drug, currentJob.Location, currentJob.Vehicle);

                    Console.WriteLine("[" + DateTime.Now.ToLongTimeString() + "] {0} has a job of {1}", player.name, _userRepository.GetAccount(player.name).Job);
                    if(_userRepository.GetAccount(player.name).Job != "Cop")
                    {
                        //API.sendChatMessageToPlayer(player, "A new shipment of {0} has arrived at the following location: {1}", );
                    }
                }

                Console.WriteLine("[" + DateTime.Now.ToLongTimeString() + "] Dealer Job thread Paused for {0} seconds", sleepfor / 1000);
                Thread.Sleep(sleepfor);
                Console.WriteLine("[" + DateTime.Now.ToLongTimeString() + "] Dealer Job thread resumes");
                i--;
            }

            Console.WriteLine("[" + DateTime.Now.ToLongTimeString() + "] Dealer Job Ends thread");
        }

        public void PlayersOnServer()
        {
            // the thread is paused for 5000 milliseconds
            int sleepfor = 5000;
            List<Client> players;

            // make thread loop endlessly until a user connects
            do
            { 
                players = API.getAllPlayers();
                Console.WriteLine("[" + DateTime.Now.ToLongTimeString() + "] Checking Player Count: {0}", players.Count);
                if (players.Count == 0)
                    Thread.Sleep(sleepfor);

            } while (players.Count == 0);
        }
    }
}

When I run the server with my resource added I get an error and the server crashes when the following line of code is reached:

int numberOfJobs = _drugDealerJobRepository.CountJobs();

I have removed the sensitive data from the connection string but it is working correctly because if I remove the line thats casuing the error then the following line works as expected returning the job data:

DrugDealerJob currentJob = _drugDealerJobRepository.GetJob(new Random().Next(1, numberOfJobs));

I can't seem to work out how to use visual studio to debug my scripts. If someone has a clue how to do this then I would appreciate the help on that.

The application connects to a mysql database via the interface which references the procedures that I have created in the mysql database.

Procedure CountJobs (No Parameters):

SELECT COUNT(*)
FROM drugdealerjobs

Procedure GetJob (Parameter jobid):

SELECT
t1.jobid
,t1.drug
,t1.unitbuyprice
,t1.unitsaleprice
,t1.location
,t1.vehicle
,t1.vehiclehash
,t2.x
,t2.y
,t2.z
FROM drugdealerjobs AS t1
INNER JOIN jobcoordinates AS t2
ON t1.jobid = t2.jobid
WHERE t1.jobid = jobid

Any ideas what I could be doing wrong? I think its something to do with the interface definition but could use some help.

Many thanks Comic Coder