var connectionString = "Data Source=transations;Mode=Memory;Cache=Shared";
using (var connection1 = new SqliteConnection(connectionString))
using (var connection2 = new SqliteConnection(connectionString))
{
    connection1.Open();
    connection2.Open();

    connection1.ExecuteNonQuery("CREATE TABLE Data (Value); INSERT INTO Data VALUES (0);");

    using (connection1.BeginTransaction())
    using (connection2.BeginTransaction())
    {
        connection1.ExecuteNonQuery("SELECT * FROM Data");
        connection2.ExecuteNonQuery("SELECT * FROM Data");

        // Each command is waiting for the other transaction to complete
        connection1.ExecuteNonQuery("UPDATE Data SET Value = 1");
        connection2.ExecuteNonQuery("UPDATE Data SET Value = 2");
    }
}