Orchid XP v8 wrote:
> The way I heard it, before databases came along, if you had a dozen 
> programs that all accessed the same pot of data, they all had to 
> understand the same file format. And if you *changed* that file format, 
> all your programs broke - usually be silently producing gibberish 
> instead of real data. Then you'd have to go modify them all one by one 
> to fix them.

Well, yes.

> The thing about a database is... the DBMS knows how to read the data. 
> And if you change how the data is stored (e.g., add a new field, change 
> a table from heap-organised to index-organised, etc.), as long as the 
> DBMS still knows how to read it, the client applications don't need to 
> *care*, and they don't break.

Well, no. That's true of RDBMs, which is why they were revolutionary. It 
isn't true of database engines that were around before the relational model.

> (Hell, if you add new fields or change the type of existing ones, you 
> can even create a "view" for the old apps to work off. They'll never 
> know the difference!)

Yes. That was the amazingly cool thing about relational databases that you 
didn't get out of CODASYL databases or hierarchical databases or whatever.

-- 
   Darren New, San Diego CA, USA (PST)
   "Ouch ouch ouch!"
   "What's wrong? Noodles too hot?"
   "No, I have Chopstick Tunnel Syndrome."

Post a reply to this message