# Thread: find all the candidate keys.

1. Registered User
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## find all the candidate keys.

Would someone please confirm that I have done this correctly. I would really appriciate it.

Find all of the candidate keys

R(ABCDEF)
F={AB > C, C > A, BC > D, ACD > B, D > EF, BE > C, CF > BD, CE > A}

A = {A}
B = {B}
C= {C,A}
D= {D,E,F}
E = {E}
F= {F}
______________

AB = {A,B,C,D,E,F}
AC={A,C}
AE={A,E}
AF={A,F}
BC={B,C,A,D,E,F}
BD={B,C,A,D,E,F}
BE={B,C,A,D,E,F}
BF={B,F}
CD={C,A,D,E,F}
CE={C,A,E}
CF={C,A,E,B,D}
DE={D,E,F}
DF={D,E,F}
EF={E,F}
________________

ABC={A,B,C,D,E,F}
ACD={A,B,C,D,E,F}
AEF={A,E,F}
BCD={A,B,C,D,E,F}
BDE={A,B,C,D,E,F}
BEF={A,B,C,D,E,F}
CDE={A,B,C,D,E,F}
CEF={A,B,C,D,E,F}
DEF={D,E,F}
________________

KEYS:
AB
BC
BD
BE
ACD
ABC
BCD
BDE
BEF
CDE
CEF

2. vaguely human
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this wouldn't be homework by any chance would it?

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phrased like that... no way is it homework, c'mon Mike get a grip

...as if

4. Registered User
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wh am I not allowed to get help here. Usually in most forums, when a poster makes a valid attempt, the user community is more than happy to help.

5. vaguely human
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No-one is stopping you from getting a better mark in your homework. It's just we'd rather you put in the effort yourself rather than asking professionals to finish it off for you. Of course if you have a particular question on database theory then we'll be happy to help. Would your lecturer be keen on the idea of his students getting help in this way to do their homework? and if not, do you think it might be because he'd view this as cheating?

6. Registered User
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This is clearly not cheating as the homework is not being graded. And I did finish it mylself. I am only asking for some confirmation that I did it correctly. I would rather find out if I am wrong now, and correct my mistakes than to find out during class next Thursday.

7. SQL Consultant
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would it be okay if we told you next friday?

8. Registered User
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Look, if I can't get help here, I will just go somewhere else. Obviously this place does not operate like other forums. All I wanted was some guidance. It is a shame that the users here are very imature.

9. SQL Consultant
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Originally Posted by gammaman
Obviously this place does not operate like other forums.
yup, and we see our reluctance to just hand out homework answers as a good thing

10. Super Moderator
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Originally Posted by r937
...we see our reluctance to just hand out homework answers as a good thing
It's good for you, as you learn the subject, not learn how to copy/paste.

It's good for us, as we don't get stuck working with/covering for someone who only knows how to copy/paste

It's good for our employers, as THEY don't have to spend money firing an incompetent, and hiring someone else. Nor do they have to pay us to fix things that could have been done correctly the first time around...

11. Resident Curmudgeon
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Originally Posted by gammaman
Look, if I can't get help here, I will just go somewhere else. Obviously this place does not operate like other forums. All I wanted was some guidance. It is a shame that the users here are very imature.
You've got a good point, if you can't get an answer here you can certainly look elsewhere. That's a "mixed bag" in that you'll get many answers of varying quality and from different degrees of background and insight, but you probably don't have the experience to efficiently separate the wheat from the chaff yet.

You've gotten rougher treatment than I think you deserve. You've presented a good bit of work and asked for confirmation.

The problem is that we (the members of DBForums) have been abused so much, for so long, by so many that we've become very skeptical of students looking for help with homework. Many of us have hired folks that managed to pass classes by turning in what was effectively plagerized homework. This is very, very disappointing to us because we spend weeks or months trying to get the new person to "live up to their potential" only to discover that they have no potential... All of their work has been effectively "stolen" from others, leaving us holding the bag (and I won't go into what the bag is full of at that point).

Your best bet is to either discuss this with your lecturer or one of their assistants. If that isn't possible, compose a few specific questions about the work you've done so far. I'm pretty sure that you'll get more open and helpful responses to specific questions than a simple "Is this Ok to turn in?" kind of question. The conversation that ensues will almost certainly get you to the point where you're confident in your answer or it will help you develop better/more specific questions.

I understand that you feel you've gotten a raw deal, and that feeling is justified. On the other hand, we've gotten an equally raw deal, spread over years, that has cost us actual time/work/money. Work with us a bit, I'll make an effort to work with you.

-PatP

12. Registered User
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OK then just answer this. In my original post for the double attribute AB, can I say that AB > C and then since the set now has {ABC} can I then say that BC goes to D and then D > EF to get a complete set, OR must I say that since BC > D and D > EF that BC >EF, if so than how do I get D for attibute AB?

13. Resident Curmudgeon
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Originally Posted by gammaman
OK then just answer this. In my original post for the double attribute AB, can I say that AB > C and then since the set now has {ABC} can I then say that BC goes to D and then D > EF to get a complete set...
Sorry, I've been up to my eyebrows in work. The first of the two plans you discussed is correct.

-PatP

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