Titlebook: Database Design and Relational Theory; Normal Forms and All C. J. Date Book 2019Latest edition C. J. Date 2019 Database Design.Functional D

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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.

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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.

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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:

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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.)

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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.

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