Re: [Phpgroupware-developers] Re: timestamps with my MySQL in schema_proc

[Michael Dean]

On Wed, 2003-06-11 at 05:12, Chris Weiss wrote:
> I've just started in on this part of mssql, never had a need before, but 
> there is a
> uniuqeidentifer type that when used with a default of newid() will give a 
> GUID and
> doesn't change for the row.  the timestamp is not just unique to the row, but 
> also
> unique to the UPDATE to the row and changes with every UPDATE.  I just even 
> started
> to look at this yesterday (doing a sync app...stupid mssql replication across
> domains and no good way to do a trust over the client side vpn, bleh) so I 
> haven't
> looked at what this value represents but I expect it to be larger with each 
> update
> as some representation of passing time.
> 
> not that any of this is usefull in a cross platform way, just fun stuff to 
> show that
> all RDBMS are not only not equal but certain ones like to invent their own
> definitions of what otherwise looks like standard features.  timestamp is not 
> a
> standard feature.

Yeah - I did figure a few years back MSSQL 7 did have a predictable
pattern and it *seemed* to represent time.  It almost looked like
seconds since 1990 IIRC.  I don't believe MSSQL2K is the same, tho.  It
looks more like a unique ID that has no direct relationship to a single
point in time.  I generally avoid them, but I have used one recently to
provide paging ability in a report.

GUIDs are useful for creating a global ID that you can reference among
several instances of databases and applications.  They're the same type
as GUIDs used to identify COM components.

Mike