title: Using clock ticks as random number seed
body: <p>I'm using the current clock ticks as a seed for random number generation. The random number is used in a pseudo GUID and a check in my database will make sure it doesn't already exist before returning. On average, this method will be called around 10k times in succession during the life of the process.</p>
  
  <p>My concern is that an identical number might be generated back to back resulting in multiple unnecessary recursive calls to my database checking for the same ID. I'd like to avoid this if possible. What is the best way to test this scenario?</p>
  
  <p>If it matters, application is .NET 4 and database is SQL Server 2008.</p>
  
  <pre><code>private static string GenerateUniqueDelId()
  {
      // Generate a random integer using the current number of clock ticks as seed.
      // Then prefix number with "DEL" and date, finally padding random integer with leading zeros for a fixed 25-character total length.
      int seed = (int)DateTime.Now.Ticks;
      Random number = new Random(seed);
      string id = string.Format("DEL{0}{1}", DateTime.Today.ToString("yyyyMMdd"), number.Next().ToString("D14"));
  
      // Lookup record with generated ID in Sesame. If one exists, call method recursively.
      string query = "SELECT * FROM Lead WHERE Esm_Id = @Esm_Id";
      SqlParameter[] parameters = { new SqlParameter("@Esm_Id", id) };
      if (DataManager.GetRow(query, parameters, DelConnection.Sesame) != null) return GenerateUniqueDelId();
  
      // Otherwise, return ID.
      return id;
  }   //// End GenerateUniqueDelId()
  </code></pre>