Hi All, I've been taking a look at DB Designer 4, and looking through the documentation (http://www.fabforce.net/dbdesigner4/doc/index.html) I am a little unclear on some of their nomenclature: '1:1' - Ok, one to one. Got it. '1:1 generalization' - Don't know this. Obviously different somehow from one to one, but how? '1:n' - One to many, I assume. '1:n non identifying' - Nonidentifying? What does this mean? 'n:m' - Many to many? Again, not sure. Can anyone help clarify? Thanks! -Josh

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9/30/2004 9:30:31 PM

Joshua Beall wrote: > I've been taking a look at DB Designer 4, and looking through the > documentation (http://www.fabforce.net/dbdesigner4/doc/index.html) I am a > little unclear on some of their nomenclature: > > '1:1' - Ok, one to one. Got it. > '1:1 generalization' - Don't know this. Obviously different somehow from > one to one, but how? > '1:n' - One to many, I assume. > '1:n non identifying' - Nonidentifying? What does this mean? > 'n:m' - Many to many? Again, not sure. > > Can anyone help clarify? Your question boils down to: "What do these mean in the context of that product". There are forums at the vendors website. Your chances of getting an answer are much better there.

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10/1/2004 10:52:17 AM

"mAsterdam" <mAsterdam@vrijdag.org> wrote in message news:415d36e5$0$43451$e4fe514c@news.xs4all.nl... >> Joshua Beall wrote: >> I've been taking a look at DB Designer 4,, and looking through the >> documentation (http://www.fabforce.net/dbdesigner4/doc/index.html) I am a >> little unclear on some of their nomenclature: >> >> '1:1' - Ok, one to one. Got it. >> '1:1 generalization' - Don't know this. Obviously different somehow from >> one to one, but how? >> '1:n' - One to many, I assume. >> '1:n non identifying' - Nonidentifying? What does this mean? >> 'n:m' - Many to many? Again, not sure. > > Your question boils down to: > "What do these mean in the context of that product". > There are forums at the vendors website. > Your chances of getting an answer are much better there. I actually did post to their forums, but from the way it is talked about in the documentation, I got the idea that these terms are general database terms that you should understand *before* using their product. This is why they don't bother to explain them, they just say "the common relationships (insert list) can be accessed via these buttons." I have looked through the documentation and was not able to find any further description of these terms. And nobody on their forums has responded yet. It's only been about 12 hours, though. -Josh

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10/1/2004 12:14:17 PM

Joshua Beall wrote: > mAsterdam wrote: >>>Joshua Beall wrote: >>>... nomenclature: >>> >>>'1:1' - Ok, one to one. Got it. >>>'1:1 generalization' - Don't know this. Obviously different somehow from >>>one to one, but how? I guess this is the 1/0:1, see below. >>>'1:n' - One to many, I assume. I guess this is the codependent 1:m, see below. >>>'1:n non identifying' - Nonidentifying? What does this mean? The foreign key is not part of the child key. IOW the key of the child does not include identification of the parent. >>>'n:m' - Many to many? Again, not sure. >> .... > I actually did post to their forums, but from the way it is talked about in > the documentation, I got the idea that these terms are general database > terms that you should understand *before* using their product. This is why > they don't bother to explain them, they just say "the common relationships > (insert list) can be accessed via these buttons." I have looked through the > documentation and was not able to find any further description of these > terms. I'll try to help make your guess an educated one, I apologize it is somewhat lengthy. "one to many" (1:m), "many to many" (m:n) are ways to express an aspect of how data relate. I don't know where these popped up, but they are pre-CODASYL. It has something to do with cardinality. Attempts to formalize this aspect have been incorporated in ER (Entity-Relationship) and ORM (Object Role Modeling). Both are used in the pre-design stage. Some call the design of the database when there is a ER or ORM to start with a "translation" (from the "logical" to the "physical", but I don't think there is anything physical about tables). Because some of the possible cardinalities are not at all consequential for the functional dependencies in the actual SQL-database design and others do not have enough information on how to implement them, some dismiss these (as pseudo-)formalisms and start with the table design right away. TIMTOWTDI: http://c2.com/cgi/wiki?ThereIsMoreThanOneWayToDoIt Here is one way to look at this: Relationship AB: +---+ AB - name +---+ | A |-cAB---------------------cBA-| B | +---+ BA - name +---+ max/min:min/max A, B are entities c is the cardinality: min is in [0,1] max is in [1, m] These are the possibilities: (max min) (min max) [one to one] --|0----------------------0|-- 1/0:0/1 for every A there is at most one related B, for every B there is at most one related A non-dependent --||----------------------||-- 1/1:1/1 for every A there must be exactly one related B, for every B there must be exactly one related A co-dependent --|0----------------------||-- 1/0:1/1 for every A there must be a related B, for every B there is at most one related A A is (existentially) dependent on B [many to one] -->0----------------------0|-- m/0:0/1 for every A there is at most one related B, for a B there may be related A's non-dependent -->0----------------------||-- m/1:1/1 for every A there must be a related B, for every B there is at least one related A co-dependent -->0----------------------||-- m/0:1/1 for every A there must be a related B A is dependent on B [many to many] -->0----------------------0<-- m/0:0/m no existence dependency non-dependent -->1----------------------1<-- m/1:1/m for every A there is at least one related B for every B there is at least one related A co-dependent -->1----------------------1<-- m/0:1/m for every A there is at least one related B A is dependent on B m/x:x/m, many to many or m:n relationships will be split into two relationships AJ and JA. The non-dependent ones aren't interesting. Trying to get the remaining co-dependent ones right may lead to counterproductive discussions about nothing relevant to the database design. Don't bother. Just label them "maybe problematic", and solve the real problems (they appear later, at design time) with adequate domain knowledge. That leaves just two types of dependencies as relevant, 1/0:1/1, and m/0:1/1. In 1/0:1/1 A may be a specialization of B, B a generalization of A. HTH

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10/1/2004 6:12:32 PM

Joshua Beall wrote: > mAsterdam wrote: >>> Joshua Beall wrote: >>> ... nomenclature: >>> >>> '1:1' - Ok, one to one. Got it. >>> '1:1 generalization' - Don't know this. >>> Obviously different somehow from >>> one to one, but how? I guess this is one to zero or one. >>> '1:n' - One to many, I assume. >>> '1:n non identifying' - Nonidentifying? What does this mean? The foreign key is not part of the child key. IOW the key of the child does not include identification of the parent. >>> 'n:m' - Many to many? Again, not sure. > ... I actually did post to their forums, but from the way it is > talked about in the documentation, I got the idea that these > terms are general database terms that you should understand > *before* using their product. This is why they don't bother > to explain them, they just say "the common relationships > (insert list) can be accessed via these buttons." > I have looked through the documentation and was not able to > find any further description of these terms. "one to many" (1:m), "many to many" (m:n) are ways to express an aspect of how data relate. I don't know where these popped up, but they are pre-CODASYL. It has something to do with cardinality. Attempts to formalize this aspect have been incorporated in ER (Entity-Relationship) and ORM (Object Role Modeling). Both are used in the pre-design stage. Some call the design of the database when there is a ER or ORM to start with a "translation" (from the "logical" to the "physical", but I don't think there is anything physical about tables). Because some of the possible cardinalities are not at all consequential for the functional dependencies in the actual SQL-database design and others do not have enough information on how to implement them, some dismiss these (as pseudo-)formalisms They start with the table design right away. Down's law: "People understand tables just fine." Very recent discovery ;-) TIMTOWTDI: http://c2.com/cgi/wiki?ThereIsMoreThanOneWayToDoIt Here is one way to look at these cardinalities: Association (Relationship) AB: +---+ AB - name +---+ | A |-cAB---------------------cBA-| B | +---+ BA - name +---+ A, B are entities cAB is the cardinality minimum and maximum: min is in [0,1] max is in [1, m] e.g.: A -->0----------------1<-- B m/0:1/m for every A there is at least one B A is dependent on B Many to many (m:n) relationships/associations will be split into two: AJ and JB. (J for Junction) Trying to get the associations with the same minimum on both sides right is a pain and does nothing to help the database design. Don't bother. Just label them "maybe problematic", and only solve the problems which are still there when you get there (they appear later, at design time) with adequate domain knowledge. That leaves just three types of dependencies as relevant, 1/0:1/1, m/0:1/1 (identifying) and m/1:0/1 (non-identifying). In 1/0:1/1 A may be a specialization of B, B a generalization of A. HTH

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10/1/2004 8:41:07 PM

Joshua Beall wrote: > mAsterdam wrote: >>> Joshua Beall wrote: >>> ... nomenclature: >>> >>> '1:1' - Ok, one to one. Got it. >>> '1:1 generalization' - Don't know this. >>> Obviously different somehow from >>> one to one, but how? I guess this is one to zero or one. >>> '1:n' - One to many, I assume. >>> '1:n non identifying' - Nonidentifying? What does this mean? The foreign key is not part of the child key. IOW the key of the child does not include identification of the parent. >>> 'n:m' - Many to many? Again, not sure. > ... I actually did post to their forums, but from the way it is > talked about in the documentation, I got the idea that these > terms are general database terms that you should understand > *before* using their product. This is why they don't bother > to explain them, they just say "the common relationships (insert list) can be accessed via these buttons." I have looked through the documentation and was not able to > find any further description of these terms. "one to many" (1:m), "many to many" (m:n) are ways to express an aspect of how data relate. I don't know where these popped up, but they are pre-CODASYL. It has something to do with cardinality. Attempts to formalize this aspect have been incorporated in ER (Entity-Relationship) and ORM (Object Role Modeling). Both are used in the pre-design stage. Some call the design of the database when there is a ER or ORM to start with a "translation" (from the "logical" to the "physical", but I don't think there is anything physical about tables). Because some of the possible cardinalities are not at all consequential for the functional dependencies in the actual SQL-database design and others do not have enough information on how to implement them, some dismiss these (as pseudo-)formalisms They start with the table design right away. Downs' law: "People understand tables just fine." Very recent discovery ;-) TIMTOWTDI: http://c2.com/cgi/wiki?ThereIsMoreThanOneWayToDoIt Here is one way to look at these cardinalities: Association (Relationship) AB: +---+ AB - name +---+ | A |-cAB---------------------cBA-| B | +---+ BA - name +---+ A, B are entities cAB is the cardinality minimum and maximum: min is in [0,1] max is in [1, m] e.g.: A -->0----------------1<-- B m/0:1/m for every A there is at least one B A is dependent on B Many to many (m:n) relationships/associations will be split into two: AJ and JB. (J for Junction) Trying to get the associations with the same minimum on both sides right is a pain and does nothing to help the database design. Don't bother. Just label them "maybe problematic", and only solve the problems which are still there when you get there (they appear later, at design time) with adequate domain knowledge. That leaves just three types of dependencies as relevant, 1/0:1/1, m/0:1/1 (identifying) and m/1:0/1 (non-identifying). In 1/0:1/1 A may be a specialization of B, B a generalization of A. HTH

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10/1/2004 8:42:13 PM

Joshua Beall wrote: > Hi All, > > I've been taking a look at DB Designer 4, and looking through the > documentation (http://www.fabforce.net/dbdesigner4/doc/index.html) I am a > little unclear on some of their nomenclature: > > '1:1' - Ok, one to one. Got it. > '1:1 generalization' - Don't know this. Obviously different somehow from > one to one, but how? > '1:n' - One to many, I assume. > '1:n non identifying' - Nonidentifying? What does this mean? > 'n:m' - Many to many? Again, not sure. > > Can anyone help clarify? > > Thanks! > -Josh > > Sorry I cant help drectly, but I would give a small warning to beware of DB Designer 4... It looks like a fabulous product, but there is a very bad bug in it: if you add then remove a relationship between tables it will destroy the the related key field in the 'destination' table. I would debug and rebuild it myself, but I gave up on Delphi a few years ago and don't think I can be bothered to port it to Freepascal/Lazarus. Mike

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10/13/2004 11:02:41 AM

"2metre" <2metre@xxxhersham.net> wrote in message news:ckj20h$6sp$1@titan.btinternet.com... > Sorry I cant help drectly, but I would give a small warning to beware of > DB Designer 4... > > It looks like a fabulous product, but there is a very bad bug in it: if > you add then remove a relationship between tables it will destroy the the > related key field in the 'destination' table. I actually discovered this - very annoying! Got suggestions for an alternative product?

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10/14/2004 1:36:01 AM

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hi my firewall logs dropped packets from an internal IP address trying to contact 1.1.1.1 through port 9999. Any ideas whether 1.1.1.1 is valid IP? and what is port 9999?? thanks mike wrote: > hi > > my firewall logs dropped packets from an internal IP address trying to > contact 1.1.1.1 through port 9999. Any ideas whether 1.1.1.1 is valid > IP? and what is port 9999?? > thanks These trojans *BlitzNet*, *Backdoor.Oracle*, *Backdoor.Spadeace* uses port 9999 -- S.S. "StarScripter" <Star@privacy.net> wrote in message news:<bv8ejj$p54t3$1@ID-185702.new...

Hi, Anybody knows how to create this matrix but without using any loops? a=[1 1 1 1 1 ;2 2 2 2 2 ;3 3 3 3 3 ;.......;n n n n n ] Thank you. Hana. Hana wrote: > Hi, > Anybody knows how to create this matrix but without using any loops? > a=[1 1 1 1 1 ;2 2 2 2 2 ;3 3 3 3 3 ;.......;n n n n n ] HELP REPMAT - Randy Hana wrote: > > > Hi, > Anybody knows how to create this matrix but without using any > loops? > a=[1 1 1 1 1 ;2 2 2 2 2 ;3 3 3 3 3 ;.......;n n n n n ] > > Thank you. > Hana. Hope this isn't homework. >> repmat([1:n]'...

Hi, How to plot those numbers in a rectangle style? thanks x = linspace(-4*pi,4*pi,1000); y = sin(x); plot(x,sign(y)), axis([-12 12 -2 2]) PZ <patrick.zou@gmail.com> wrote in message <d64c545f-f2ac-4f87-af89-051bda896707@x6g2000vbg.googlegroups.com>... > Hi, > > How to plot those numbers in a rectangle style? > > thanks help stairs stairs([-1 1 -1 1 -1 1]) hth Jos ...

#1 #n+1 #2n+1 #2 #n+2 #2n+2 #3 #n+3 #2n+3 #n #2n #3n #1 #2 #3 #n #n+1 #n+2 #n+3 #2n #2n+1 100 Gbps aggregate stream of 64/66b words virtual lane markers virtual lane 1 virtual lane 2 virtual lane 3 virtual lane n Simple 66-bit word level round robin distribution Transmit PM Transmit PM Receive PM Receive PM Transmit PC Receive PC 1 0.0 1.0 0.1 0.2 0.3 1.2 1.2 1.1 0.0 1.0 0.1 1.1 2.0 3.0 4.0 6.0 7.0 9.0 10.0 11.0 12.0 13.0 14.0 15.0 17.0 18.0 19.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 11.0 12.0 13.0 14.0 15.0 16.0 17.0 1...

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