Ordinary Dependence and Extraordinary DependenceOrdinary dependence refers to the dependence of a certain attribute set on itself in the relationship. For example, in a set composed of attributes A and B, the dependence of A and B on themselves (A→A and B→B) is trivial dependence. In a table that stores student performance information, the set of attributes {SNo, CNo, Score},{SNo} → SNo,{CNo, Score} → Score, etc. are also trivial dependence.
Nontrivial dependence is if X → Y holds and Y does not belong to X. For example, in a student's report card,{SNo, CNo} → Score is a non-trivial dependence because Score does not belong to the combination key {SNo, CNo}.
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Is ordinary dependence the same as extraordinary dependence?Ordinary dependence was different from extraordinary dependence. A trivial dependence refers to a property or property set that is completely dependent on itself. For example, in the relationship R(A, B), A -> A and B -> B are trivial dependence. The non-ordinary dependence was not the dependence of this attribute collection on oneself. In the process of database normalisation, trivial dependence had no practical effect and would not affect the integrity or integrity of the database design. It was more used to define and identify more complex dependence relationships, such as functional dependence, partial dependence, and transitive dependence. Non-trivial dependence had different effects and meanings in the design of the database.
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The difference between ordinary dependence and extraordinary dependenceOrdinary Dependence referred to the fact that a certain attribute in the attribute set depended on itself and did not need to obtain information from other attributes. For example, in a table containing the property set {SNo, CNo, Score},{SNo} → SNo, {CNo, Score} → Score is a trivial dependence.
A non-trivial dependence is a non-trivial dependence if X → Y is true and Y does not belong to X. For example, in the student report,{SNo, CNo} → Score is a non-trivial dependence, because the score Score does not belong to the combination key {SNo, CNo}.
In summary, the main difference between the two was that ordinary dependence was the dependence of attributes on themselves, while non-ordinary dependence was the dependence of an attribute (set) on another attribute (set) that did not belong to itself.
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trivial functional dependence and partial functional dependenceBased on context alone
1. ** Ordinary Function Dependence **
- In a database, let R(U) be a relation pattern on a set of attributes U, and X and Y be a set of attributes U. If Y is a sub-set of X (that is, Y X), then X→Y is a trivial functional dependence.
- For example, in the relationship mode of students (student number, name, gender),{student number, name}→{name} is a trivial functional dependence, because the name itself is a part of {student number, name}. Semantically speaking, trivial functional dependence represented an obviously established dependence relationship. This dependence relationship did not actually contain much meaningful new information, because it only indicated that the dependence of a set of attributes on its own set must exist.
2. ** Part of Function Dependence **
- Let (X,Y) be the property set of the relation pattern (R). If (X→Y) exists a proper set of (X ') such that (X'→Y), then (Y) is partially dependent on (X).
- For example, in the Relational Mode course selection (student number, course number, grades, course name),{student number, course number}→{course name}, but in fact,{course number}→{course name}, which meant that the course name only depended on the student number and the course number in the course number, not the entire {student number, course number}, so the course name was partially dependent on {student number, course number}. Partial functional dependence may cause data redundancy-like problems. In the standardized design of a database, it is usually necessary to eliminate partial functional dependence to achieve a higher standard.
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Dependence, is it love?Dependence and liking were two different concepts. The sense of dependence was produced when one's own value relationship was restricted by the value relationship of others. It was more reflected in the hope that the other party would continue to pay attention to oneself and accompany oneself when one was tired and bored. It was a feeling of relying on others. Liking someone was usually established between two independent personalities. It was more about having a good impression or interest in someone or something. It was a relatively positive emotion. For example, one wanted to share their happiness with the other party. They did not only need the other party's company when they were sad. Therefore, dependence was not like.
Non-trivial functional dependence and trivial functional dependenceLet X and Y be the attributes of a relation, and X→Y. If Y is contained in X, then X→Y is called a trivial functional dependence. If Y is not contained in X, then X→Y is called a non-trivial functional dependence. The trivial functional dependence was automatically established because it was determined by the reflexive nature of the functional dependence. The functional dependence that was generally studied was mostly non-trivial functional dependence.
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Long-term dependenceChangxiang Yi's simplified musical scores could be found on many websites, such as the music website, the Chinese music website, and the music website. This song's simplified musical score was in the key of G, and it could also be in 2nd grade. In addition, there were also some related articles and recommendations that could be used as reference.
Dependence on romance novelsRomance novel dependence usually refers to a kind of dependence that occurs when reading romance novels. That is, readers may be too obsessed with the plot and characters in the novel and ignore the real life and emotional needs. This phenomenon was more common among some young people and might affect their studies and lives.
Romance novels often depicted romantic and beautiful love plots that readers might resonate with and feel emotionally satisfied. However, over-reliance on romance novels may cause readers to lack awareness and understanding of real-life feelings and interpersonal relationships, and even affect their social skills and self-confidence in real life.
Therefore, when reading romance novels, readers need to maintain the ability to think rationally and independently. They should not rely too much on the plot and characters in the novel, nor should they use the plot and characters in the novel as a template and substitute for reality. At the same time, readers also need to pay attention to real life and emotional needs, and actively seek and cultivate their own emotional sustenance and emotional support.
Rebirth of the Doomsday DependenceI recommend a few apocalyptic novels. Reforming the End of the World, Zuo An Zuo Zuo's creation, completed. This was an apocalyptic novel of the rebirth system. The protagonist had six years of experience in the apocalypse and was reborn back to the beginning of the apocalypse. It was purely a fight for hegemony, without harem or stallion. The plot was smooth. Although the ending wasn't satisfactory and the later parts were a little out of control, the overall situation was not bad. The author's writing style was good, but the updates were a little slow.
" The Return of Rebirth in the End of the World ", a fantasy romance novel written by Little Corpse who had no sense of direction. The female protagonist was reborn on the eve of the apocalypse. She only lived for the people she cared about and was no longer at the mercy of others.
" Revenge of Rebirth in the End of the World ", a sci-fi space series created by Meowlemeow. After the female protagonist was betrayed, she was reborn a year before the apocalypse and wanted the person who owed her to pay back.
"Double Pet of Rebirth Doomsday" by Bai Xiaozhen. The male protagonist was reborn, and the female protagonist had transmigrated. It was a super sweet doomsday favorite novel. It did not have the cruel oppression of ordinary doomsday novels. The characters were vividly created, and the team was very warm.
" Doomsday Survival Master " was written by Taiping Steamed Bun. Although it had been censored, it was still worth reading. The protagonist wanted to protect his family before he was reborn. The plot and setting were reasonable, the rhythm was tight, and it was dark.
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