Multiple access to a single SQLite database file via System.Data.SQLite and c#

Question

As I can read from SQLite FAQ it supports multiple processes reading (SELECT) and only one process writing (INSERT, UPDATE, DELETE) database at any moment in time:

Answer 1

I've investigated it by myself:

I created a sample SQLite database c:\123.db with one table Categories containing two fields: ID (uniqueidentifier) and Name (nvarchar).

I then wrote some multi-thread code to emulate multiple write access to the database (don't forget to add a System.Data.SQLite reference to your project if you use this code):

using System;
using System.Data.SQLite;
using System.Threading.Tasks;

namespace SQLiteTest
{
    class Program
    {
        static void Main(string[] args)
        {
            var tasks = new Task[100];

            for (int i = 0; i < 100; i++)
            {
                tasks[i] = new Task(new Program().WriteToDB);
                tasks[i].Start();
            }

            foreach (var task in tasks)
                task.Wait();
        }

        public void WriteToDB()
        {
            try
            {
                using (SQLiteConnection myconnection = new SQLiteConnection(@"Data Source=c:\123.db"))
                {
                    myconnection.Open();
                    using (SQLiteTransaction mytransaction = myconnection.BeginTransaction())
                    {
                        using (SQLiteCommand mycommand = new SQLiteCommand(myconnection))
                        {
                            Guid id = Guid.NewGuid();

                            mycommand.CommandText = "INSERT INTO Categories(ID, Name) VALUES ('" + id.ToString() + "', '111')";
                            mycommand.ExecuteNonQuery();

                            mycommand.CommandText = "UPDATE Categories SET Name='222' WHERE ID='" + id.ToString() + "'";
                            mycommand.ExecuteNonQuery();

                            mycommand.CommandText = "DELETE FROM Categories WHERE ID='" + id.ToString() + "'";
                            mycommand.ExecuteNonQuery();
                        }
                        mytransaction.Commit();
                    }
                }
            }
            catch (SQLiteException ex)
            {
                if (ex.ReturnCode == SQLiteErrorCode.Busy)
                    Console.WriteLine("Database is locked by another process!");
            }
        }
    }
}

The result on my Core2Duo E7500 is that Exception is never raised!

Looks like SQLite is optimised enough for my needs (locking/unlocking is really fast and normally only takes a few milliseconds as SQLite FAQ tells us) - Great!

Note that there is no need to retrieve an integer ErrorCode for an SQLiteException - you can use a special enum ReturnCode field instead. All codes are described here.

Hope this information will help somebody.