Dec 16, 2008 · GUID (or UUID) is an acronym for 'Globally Unique Identifier' (or 'Universally Unique Identifier'). It is a 128-bit integer number used to identify resources. The term GUID is generally used by developers working with Microsoft technologies, while UUID is used everywhere else.

Jan 15, 2011 · It is much larger than a typical auto-increment integer, but it makes replication and migration much easier - data from two previously unrelated databases will not produce collisions on the primary keys if you use GUIDs, because each GUID is (conceptually) globally unique.

If you need unique identifiers generated across multiple servers, GUIDs may be useful. If you need mondo perforance and under 2 billion values, ints are probably fine. Lastly and perhaps most importantly, if your data has natural keys, stick with them and forget the surrogate values.

May 7, 2010 · For detailed instructions on how to get a unique identifier for each Android device your application is installed from, see the official Android Developers Blog posting Identifying App Installations. It seems the best way is for you to generate one yourself upon installation and subsequently read it when the application is re-launched.

Apr 15, 2009 · The reference is the unique identifier for the object. I don't know of any way of converting this into anything like a string etc. The value of the reference will change during compaction (as you've seen), but every previous value A will be changed to value B, so as far as safe code is concerned it's still a unique ID.

Dec 16, 2009 · In this case however even the SID would change since it is considered a new account, even though it is actually the same person. If you want to truly ensure that its the same person then you would need to use a globally recognized unique identifier such as SSN. –

Aug 10, 2009 · Due to a rather brilliant oversight in my current project, we have some guids getting stored in a varchar column in one table, which need to be compared to a uniqueidentifier column in another.

I don't understand what you're trying to achieve. You want to select all of the rows where the value for a certain column is a unique identifier? What's the business scenario? And if a column is meant to hold a uniqueidentifier, won't its value either be null or be, in fact, a uniqueidentifier? What else could it be? –

Nov 17, 2016 · it will take less space; it's unique so it can not be duplicated. It's much better for comparisons and specially performance related issues as well as easy to get unique default value etc. I would use uniqueidentifier unless I need to use varchar for very specific reason.

Jan 26, 2011 · thanks Dan, but i was hopign for an incramental unquie identifier (i.e. 0001, 0002, 0003) is that at all possible? – James Parish Commented Jan 26, 2011 at 10:19