標(biāo)題: Titlebook: Database Design and Relational Theory; Normal Forms and All C. J. Date Book 2019Latest edition C. J. Date 2019 Database Design.Functional D [打印本頁] 作者: Buchanan 時間: 2025-3-21 18:44
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作者: perpetual 時間: 2025-3-21 23:54
Preserving FDs {SNO}, . as {STATUS}, and . as {SNAME,CITY}, Heath’s Theorem tells us we can decompose that relvar into relvars SNC and ST, where SNC has heading {SNO,SNAME,CITY} and ST has heading {SNO,STATUS}. Sample values for SNC and ST corresponding to the value shown for S in Figure 3-1 are shown in Figure 6-1:作者: micronutrients 時間: 2025-3-22 04:22 作者: 過剩 時間: 2025-3-22 08:02 作者: VICT 時間: 2025-3-22 10:13 作者: 玩忽職守 時間: 2025-3-22 16:47 作者: 玩忽職守 時間: 2025-3-22 18:01
Thinking About Justice and Interpreting the s for the small amount of repetition involved). As you’ll quickly see, the treatment in this chapter is rather more abstract than that in the previous one; it shouldn’t be too difficult to follow, if you’re fully comfortable with the material of that previous chapter, but it’ll certainly be more for作者: 喪失 時間: 2025-3-23 00:38
https://doi.org/10.1007/978-981-99-5471-1 {SNO}, . as {STATUS}, and . as {SNAME,CITY}, Heath’s Theorem tells us we can decompose that relvar into relvars SNC and ST, where SNC has heading {SNO,SNAME,CITY} and ST has heading {SNO,STATUS}. Sample values for SNC and ST corresponding to the value shown for S in Figure 3-1 are shown in Figure 6作者: 不透明 時間: 2025-3-23 05:27 作者: 食物 時間: 2025-3-23 08:01
Social Organizations and Governments); as noted in Chapter ., in fact, 5NF is . normal form with respect to JDs, just as BCNF is . normal form with respect to FDs. And the treatment of these ideas in this part of the book therefore parallels the treatment of BCNF and FDs in Part II. In other words, I plan to treat the material both f作者: 替代品 時間: 2025-3-23 12:48 作者: 圣歌 時間: 2025-3-23 15:09
https://doi.org/10.1007/978-94-015-1276-3 FDs are implied by other FDs, and we saw in Chapters 9 and 10 how some JDs are implied by FDs. It’s time to take a closer look at such matters. Note that if we need to tell what normal form some given relvar is in, we do need to know all of the dependencies, implicit ones as well as explicit ones, 作者: 津貼 時間: 2025-3-23 19:42
https://doi.org/10.1007/978-90-481-8620-4 as the present chapter is concerned—any redundancy that can be removed by taking projections. And of course we use the discipline of further normalization, or just normalization for short, to help us reach that goal. Now, for many years it was believed that a relvar had to be in fifth normal form (作者: 南極 時間: 2025-3-24 02:15
Maria I. New M. D.,Lenore S. Levine M. D.rojection as the decomposition operator and join as the corresponding recomposition operator. I also said in that same chapter that, given that assumption, it followed that 5NF was the final normal form. However, I did also say in a footnote to that chapter that there was something called . normal f作者: 托人看管 時間: 2025-3-24 04:00 作者: Digitalis 時間: 2025-3-24 09:33
https://doi.org/10.1007/978-1-4842-5540-7Database Design; Functional Dependence; Multivalued Dependence; Join Dependence; Boyce-Codd Normal Form 作者: Organization 時間: 2025-3-24 13:42 作者: 壟斷 時間: 2025-3-24 16:30 作者: Aids209 時間: 2025-3-24 20:06
Which Confucianism? And What Liberty?ty with relational theory. Please note that—I’m sorry to have to say this, but it’s true—a knowledge of SQL, no matter how deep, is . sufficient to satisfy part (b) of this requirement. As I said in .:作者: Anonymous 時間: 2025-3-25 01:45 作者: 娘娘腔 時間: 2025-3-25 06:48
A Discussion on Several Translated Terms of , not in detail). But denormalization, if it means anything at all, can’t apply just to BCNF specifically; I mean, it can’t refer just to dropping back to some level of normalization that’s lower than BCNF specifically. Rather, it has to mean dropping back from . given level of normalization to some lower one.作者: orthopedist 時間: 2025-3-25 10:41 作者: 蔓藤圖飾 時間: 2025-3-25 14:06 作者: Ptsd429 時間: 2025-3-25 16:19 作者: 秘密會議 時間: 2025-3-25 20:59 作者: frozen-shoulder 時間: 2025-3-26 02:18
FD AxiomatizationI’ve touched on the point several times already that some FDs imply others; now it’s time to get more specific. First of all, however, I need to introduce some notation—notation that (a) reduces the number of keystrokes required in formal proofs and the like and (b) can also help, sometimes, to see the forest as well as the trees, as it were.作者: creditor 時間: 2025-3-26 07:34
MVDs and 4NFIn Chapter 10, I said that 4NF, like 2NF and 3NF, is mostly of historical interest. However, that characterization is possibly a little unfair, because:作者: fluoroscopy 時間: 2025-3-26 11:54
FDs and BCNF (Formal) one; it shouldn’t be too difficult to follow, if you’re fully comfortable with the material of that previous chapter, but it’ll certainly be more formal. For that reason, . (Of course, that shouldn’t be hard to do, since most of what was in that chapter was surely familiar to you anyway.)作者: aviator 時間: 2025-3-26 13:09
JDs and 5NF (Informal)these ideas in this part of the book therefore parallels the treatment of BCNF and FDs in Part II. In other words, I plan to treat the material both formally, in Chapter ., and informally in the present chapter.作者: 過于平凡 時間: 2025-3-26 17:16 作者: 膽小懦夫 時間: 2025-3-27 00:17
Implicit Dependenciesthat if we need to tell what normal form some given relvar is in, we do need to know all of the dependencies, implicit ones as well as explicit ones, that hold in that relvar. In this chapter, therefore, I plan to discuss among other things:作者: IST 時間: 2025-3-27 01:28
6NFtion, it followed that 5NF was the final normal form. However, I did also say in a footnote to that chapter that there was something called . normal form or 6NF, and that’s what the present chapter is all about.作者: overweight 時間: 2025-3-27 05:35
The End Is Not Yet the last is easily the most important). But even that’s not the end of the story. In this chapter, just for completeness, I briefly describe or at least mention a few other normal forms that have been defined in the literature at one time or another.作者: 不能和解 時間: 2025-3-27 10:15 作者: V洗浴 時間: 2025-3-27 15:44
ality.Provides friendly examples of theory without sacrificiCreate database designs that scale, meet business requirements, and inherently work toward keeping your data structured and usable in the face of changing business models and software systems..This book is about database design theory. Desi作者: 不可磨滅 時間: 2025-3-27 18:14 作者: 使糾纏 時間: 2025-3-27 23:13
Social Organizations and Governmentthese ideas in this part of the book therefore parallels the treatment of BCNF and FDs in Part II. In other words, I plan to treat the material both formally, in Chapter ., and informally in the present chapter.作者: Habituate 時間: 2025-3-28 06:07
Free Will, Benevolence and the Vision Let me just say up front that, just as Chapter . had little to say about 2NF or 3NF, so this chapter has little to say about 4NF, either; like 2NF and 3NF, in fact, 4NF is—from some points of view, at least—primarily of historical interest. However, I’ll discuss it in a little more detail in a later chapter (Chapter .).作者: AWL 時間: 2025-3-28 09:01
https://doi.org/10.1007/978-94-015-1276-3that if we need to tell what normal form some given relvar is in, we do need to know all of the dependencies, implicit ones as well as explicit ones, that hold in that relvar. In this chapter, therefore, I plan to discuss among other things:作者: LEVER 時間: 2025-3-28 13:13 作者: myriad 時間: 2025-3-28 15:36 作者: 越自我 時間: 2025-3-28 19:25
https://doi.org/10.1007/978-90-481-8620-4er, it turns out that this belief was incorrect—that is, it turns out that several other normal forms can be defined, all of them both weaker than 5NF and stronger than fourth normal form (4NF), and all of them just as effective as 5NF at eliminating redundancy. The normal forms in question are:作者: 現(xiàn)代 時間: 2025-3-28 23:37 作者: 才能 時間: 2025-3-29 04:53 作者: pessimism 時間: 2025-3-29 08:36 作者: 可忽略 時間: 2025-3-29 14:37 作者: Pepsin 時間: 2025-3-29 16:24
FDs and BCNF (Informal)us explanations and associated definitions are all intentionally a little informal at this stage. (Informal, but not inaccurate; I won’t tell any deliberate lies.) A more formal treatment of the material appears in the next chapter.作者: Lyme-disease 時間: 2025-3-29 21:11
Book 2019Latest editioncrucial notion of data consistency.Sequencing of topics has been improved, and many explanations and examples have been rewritten and clarified based upon the author’s teaching of the content in instructor-led courses.?.This book aims to be different from other books on design by bridging the gap be作者: Conducive 時間: 2025-3-30 01:06
ations and examples have been rewritten and clarified based upon the author’s teaching of the content in instructor-led courses.?.This book aims to be different from other books on design by bridging the gap be978-1-4842-5539-1978-1-4842-5540-7作者: 政府 時間: 2025-3-30 04:21
Preliminariesthat is—and everybody knows that normal forms are a major component of that theory; hence the first part of the subtitle. But there’s more to that theory than just normal forms, and that fact accounts for that subtitle’s second part. Third, it’s unfortunately the case that—from the practitioner’s po作者: abolish 時間: 2025-3-30 10:49 作者: Isometric 時間: 2025-3-30 16:11 作者: 上下連貫 時間: 2025-3-30 20:08 作者: 摘要 時間: 2025-3-30 21:07 作者: Foreknowledge 時間: 2025-3-31 02:50
Denormalization, not in detail). But denormalization, if it means anything at all, can’t apply just to BCNF specifically; I mean, it can’t refer just to dropping back to some level of normalization that’s lower than BCNF specifically. Rather, it has to mean dropping back from . given level of normalization to some作者: 緩和 時間: 2025-3-31 08:54
JDs and 5NF (Informal)s); as noted in Chapter ., in fact, 5NF is . normal form with respect to JDs, just as BCNF is . normal form with respect to FDs. And the treatment of these ideas in this part of the book therefore parallels the treatment of BCNF and FDs in Part II. In other words, I plan to treat the material both f作者: arterioles 時間: 2025-3-31 09:47
JDs and 5NF (Formal)ment of material introduced informally in Chapter .. But there’s rather more to cover in this chapter than there was in Chapter ., as you’ll soon see. Let me just say up front that, just as Chapter . had little to say about 2NF or 3NF, so this chapter has little to say about 4NF, either; like 2NF an
