hmmmm......
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I've just been asked to do something stupid with a system that we've just taken ownership of (it happens from time to time
).Basically, i've been asked if I can take n similar tables (they don't know how many there will be yet, but lets say 5 to make it simple (there's actually round 50)) and bring them all together to make one master table.
On the face of it it wasn't going to be that difficult, but after having a look at the table structures it's become apparent that not every table has all of the columns.
They do all have some common fields but it's how to handle the missing/extra ones that I'm asking about, any idea's would be most appreciated.
I'm thinking of telling them to go back and make all of the tables the same (that's a lack of standards for you), but just for my own piece of mind I'd like to know how other people would handle it.
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Well why r they asking you to merge the tables??
Are they asking you to take an apple and an orange table to make a fruits table. Or to take the customers, orders, order details, suppliers and products tables to make a huge master of a mess table?
If you don't already see where I'm going, my answer would be don't do it unless the tables contains really the same information.
If they still bug you to do it, then maybe you could do an indexed view on those tables... But the performance hit to keep all 50 tables up to date in the view could be gigantic.
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I've just expained that in order for the tables to be merged they'd all need the same structure, my time is way too expensive to waste on it; so if they want the mess that will result from it then they can spend the time getting it right up front.
What's the betting that I don't hear anything more about it after they've done a couple of tables themselves
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That'd be a good plan.... make 'em do the work for you... then show 'em why it wasn't a good idea to start with... then they would stop ignoring your advices
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In actuality, the users requesting the change have all the knowledge needed, after all it is a business process and business decision driving this. What they are probably lacking are the needed skills to attempt to 'de-normalize' (make a mess) of things. If they insist on following through then you will still be involved on a nickel and dime basis as opposed to an alll out effort. Maybe giving them something to read about data and normalization might help (better yet deter them from the task altogether). Might I suggest:
http://www.sswug.org/see/22707
Now to really confound them:
http://www.wildewood.co.uk/comp/more/codds_rules.html
RegardsRudy KomacsarSenior Database Administrator"Ave Caesar! - Morituri te salutamus."
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My gut reaction is that your employers really want you to create a view, so that they can see similar objects in one data structure.
If the entities are different, they probably belong in separate tables, and a view may be all that is needed for them to do some reporting.
HTH
Jonathan Starr
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