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"Real" copy of Codd's 12 (13) Rules for RDBMS Expand / Collapse
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Posted Monday, August 16, 2010 7:46 PM


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mtillman-921105 (8/16/2010)
I was a philosophy major (and a psychology major by the way), so I started reading my book on elemetary logic about empty sets over the weekend. Now here is the clencher - it said that an empty set was represented by a zero.


I won't argue that an "empty set" is represented by a zero but that has nothing to do with NULL's in a database.

Again, you should have just stopped where you were because that's all that matters about NULL's in a DB.


--Jeff Moden
"RBAR is pronounced "ree-bar" and is a "Modenism" for "Row-By-Agonizing-Row".

First step towards the paradigm shift of writing Set Based code:
Stop thinking about what you want to do to a row... think, instead, of what you want to do to a column."

"Change is inevitable. Change for the better is not." -- 04 August 2013
(play on words) "Just because you CAN do something in T-SQL, doesn't mean you SHOULDN'T." --22 Aug 2013

Helpful Links:
How to post code problems
How to post performance problems
Post #970107
Posted Tuesday, August 17, 2010 2:16 AM
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Hi Jeff,
Here you'll find 3 papers from E.F.Codd ,
A Relational Model of Data for Large Shared Data Banks
http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.98.5286&rep=rep1&type=pdf
Extending the Database Relational Model to Capture More Meaning
http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.84.9469&rep=rep1&type=pdf
RELATIONAL COMPLETENESS OF DATA BASE SUBLANGUAGES
http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.86.9277&rep=rep1&type=pdf

HTH
Alain
Post #970184
Posted Tuesday, August 17, 2010 5:32 AM


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mtillman-921105 (8/16/2010)
I was a philosophy major (and a psychology major by the way), so I started reading my book on elemetary logic about empty sets over the weekend. Now here is the clencher - it said that an empty set was represented by a zero.

Did the book really say "a zero", or did you mistake the Greek letter phi (φ or Φ) - which is the usual symbol used to denote the empty set - for a 0? Or do you have it upside down, did it actually say "in standard set theory the empty set is used to denote the (ordinal) number zero"? It's quite possible that you are quoting correctly and your elementary logic did say something quite bizarre, but in my experience the most common reason for someone to claim that the empty set is represented by 0 is one of those two misunderstandings. Mistaking Φ for 0 is particularly common amongst those who grew up with batch computoing, since there was a fairly common convention that on coding sheets phi should be used for zero and theta for letter "O" in order to disambiguate them for the girls who typed from the coding sheets, whether to produce punched cards, or paper tape, or for direct data entry to the computer; perhaps your book was written - or proof-edited - by someone from that generation.


Tom
Post #970269
Posted Tuesday, August 17, 2010 6:22 AM


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Tom.Thomson (8/17/2010)
mtillman-921105 (8/16/2010)
I was a philosophy major (and a psychology major by the way), so I started reading my book on elemetary logic about empty sets over the weekend. Now here is the clencher - it said that an empty set was represented by a zero.

Did the book really say "a zero", or did you mistake the Greek letter phi (φ or Φ) - which is the usual symbol used to denote the empty set - for a 0? Or do you have it upside down, did it actually say "in standard set theory the empty set is used to denote the (ordinal) number zero"? It's quite possible that you are quoting correctly and your elementary logic did say something quite bizarre, but in my experience the most common reason for someone to claim that the empty set is represented by 0 is one of those two misunderstandings. Mistaking Φ for 0 is particularly common amongst those who grew up with batch computoing, since there was a fairly common convention that on coding sheets phi should be used for zero and theta for letter "O" in order to disambiguate them for the girls who typed from the coding sheets, whether to produce punched cards, or paper tape, or for direct data entry to the computer; perhaps your book was written - or proof-edited - by someone from that generation.
I never made that connection, that's why people slash their zeroes....huh, learn something new every day...


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Post #970322
Posted Tuesday, August 17, 2010 8:13 AM


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Alain Rastoul (8/17/2010)
Hi Jeff,
Here you'll find 3 papers from E.F.Codd ,
A Relational Model of Data for Large Shared Data Banks
http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.98.5286&rep=rep1&type=pdf
Extending the Database Relational Model to Capture More Meaning
http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.84.9469&rep=rep1&type=pdf
RELATIONAL COMPLETENESS OF DATA BASE SUBLANGUAGES
http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.86.9277&rep=rep1&type=pdf

HTH
Alain


Finally! Someone get's back to the original subject of my poor ol' hijacked thread! Thanks, Alain. I'll take a look.


--Jeff Moden
"RBAR is pronounced "ree-bar" and is a "Modenism" for "Row-By-Agonizing-Row".

First step towards the paradigm shift of writing Set Based code:
Stop thinking about what you want to do to a row... think, instead, of what you want to do to a column."

"Change is inevitable. Change for the better is not." -- 04 August 2013
(play on words) "Just because you CAN do something in T-SQL, doesn't mean you SHOULDN'T." --22 Aug 2013

Helpful Links:
How to post code problems
How to post performance problems
Post #970434
Posted Tuesday, August 17, 2010 9:11 AM


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Jeff Moden (8/17/2010)
Alain Rastoul (8/17/2010)
Hi Jeff,
Here you'll find 3 papers from E.F.Codd ,
A Relational Model of Data for Large Shared Data Banks
http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.98.5286&rep=rep1&type=pdf
Extending the Database Relational Model to Capture More Meaning
http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.84.9469&rep=rep1&type=pdf
RELATIONAL COMPLETENESS OF DATA BASE SUBLANGUAGES
http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.86.9277&rep=rep1&type=pdf

HTH
Alain


Finally! Someone get's back to the original subject of my poor ol' hijacked thread! Thanks, Alain. I'll take a look.


You're right Jeff. I can take a hint, so I started a new thread on NULLs.
http://www.sqlservercentral.com/Forums/Topic970493-374-1.aspx




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Post #970496
Posted Tuesday, August 17, 2010 1:35 PM


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mtillman-921105 (8/17/2010)
Jeff Moden (8/17/2010)
Alain Rastoul (8/17/2010)
Hi Jeff,
Here you'll find 3 papers from E.F.Codd ,
A Relational Model of Data for Large Shared Data Banks
http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.98.5286&rep=rep1&type=pdf
Extending the Database Relational Model to Capture More Meaning
http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.84.9469&rep=rep1&type=pdf
RELATIONAL COMPLETENESS OF DATA BASE SUBLANGUAGES
http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.86.9277&rep=rep1&type=pdf

HTH
Alain


Finally! Someone get's back to the original subject of my poor ol' hijacked thread! Thanks, Alain. I'll take a look.


You're right Jeff. I can take a hint, so I started a new thread on NULLs.
http://www.sqlservercentral.com/Forums/Topic970493-374-1.aspx




Very cool... thanks.


--Jeff Moden
"RBAR is pronounced "ree-bar" and is a "Modenism" for "Row-By-Agonizing-Row".

First step towards the paradigm shift of writing Set Based code:
Stop thinking about what you want to do to a row... think, instead, of what you want to do to a column."

"Change is inevitable. Change for the better is not." -- 04 August 2013
(play on words) "Just because you CAN do something in T-SQL, doesn't mean you SHOULDN'T." --22 Aug 2013

Helpful Links:
How to post code problems
How to post performance problems
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