> what is the difference between a display only field showing an internal ID > number, > and a duplicate, display only ID number showing on the entry form? It really comes down to preference, you can link how you wish. A read only numeric ID works in most cases.
The reason I don't use them is that if you expose a read only ID to the business, the business owns that ID not you or the application. At that point they can request things change around that ID that would/could break your linking. Most the time you will be OK, other times it can mess you up or cause you to say "No we can't do that" to a client. As much as I like to think the business is constant and won't change, and that unique numbers stay unique, it does happen all of the time, even around read only keys. I have been around a long time and have been glad that I use internal IDs instead of business exposed keys on multiple occasions. Using keys that the client never sees, fixes this potential (in a lot of cases unlikely) problem. As for me and my databases, I link my data with keys that I own and the business can't see. I also use UUID over longint - UUID is faster (do to "random" data in the index) - UUID solves problems with distributed systems that sync - UUID fixes the home grown sequence problem with transactions - UUID is not easily readable by human and keeps me from being tempted to expose them :) Neil -- Privacy Disclaimer: This message contains confidential information and is intended only for the named addressee. If you are not the named addressee you should not disseminate, distribute or copy this email. Please delete this email from your system and notify the sender immediately by replying to this email. If you are not the intended recipient you are notified that disclosing, copying, distributing or taking any action in reliance on the contents of this information is strictly prohibited. The Alternative Investments division of UMB Fund Services provides a full range of services to hedge funds, funds of funds and private equity funds. Any tax advice in this communication is not intended to be used, and cannot be used, by a client or any other person or entity for the purpose of (a) avoiding penalties that may be imposed on any taxpayer or (b) promoting, marketing, or recommending to another party any matter addressed herein. ********************************************************************** 4D Internet Users Group (4D iNUG) FAQ: http://lists.4d.com/faqnug.html Archive: http://lists.4d.com/archives.html Options: http://lists.4d.com/mailman/options/4d_tech Unsub: mailto:4d_tech-unsubscr...@lists.4d.com **********************************************************************
