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some basic oracle questions (assertions etc)

From: <spliffmonkey_at_iname.com>
Date: 8 Dec 2005 13:49:24 -0800
Message-ID: <1134078564.361444.100590@g47g2000cwa.googlegroups.com>


I have a couple of questions. If you dont know the answer could you point me somewhere that has info on this type of basic stuff:

  1. I want to creat an assertion that states that IF A is 'yes' then B and C are NOT NULL. (whereas if A is 'no' then null is acceptable for B and C)
  2. If a table of, say, buildings requires a builder, I would specify that builder would be NOT NULL. However, if a table of buildings could have several builders (1 or more) then I would have a separate table where they both together formed a primary key. Now my question: How do you specify that a building MUST have a builder? i.e. how do you ensure that there is an entry for a particular building in the building-builder table?
  3. Whats wrong with this join?: select * from Ride, Rideservicemen where Rideservicemen.Ridename = Ride.Ridename;

When it joins the two tables, Ridename is printed twice each time?

Thanks Received on Thu Dec 08 2005 - 15:49:24 CST

Original text of this message

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