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gogolik [260]
3 years ago
10

Suppose we have a database for an investment firm, consisting of the following attributes: B (broker), O (office of a broker), I

(investor), S (stock), Q (quantity of stock owned by an investor), and D (dividend paid by a stock), with the following functional dependencies: SD, I B.IS a Find a key for the relation scheme R(B,O,S,Q,I,D). b. Find a decomposition of R into third normal form, having a lossless join and preserving dependencies c.Find a lossless join decomposition of R into Boyce-Codd normal form.
Engineering
1 answer:
Snowcat [4.5K]3 years ago
8 0

Answer:

Given, FDs are:

S -> D

I -> B

IS -> Q

B -> O

a)

"I" and "S" must be there in any candidate key because they do not appear on the right side of any functional dependency.

The only candidate key is: IS

IS -> ISBDQO

b)

Decomposition of R into 3NF: (I, B), (S, D), (B, O), (I, S, Q)

c)

Decomposition of R into BCNF:

Decompose R by I → B into R1 = (I, B) and R2 = (I, O, S, Q, D).

R1 is in BCNF

Decompose R2 by S → D into R21 = (S, D) and R22 = (O, I, S, Q).

R21is in BCNF

Decompose R22 by I → O into R221 = (I, O) and R222 = (I, S, Q).

R221 is in BCNF.

R222 is in BCNF.

The decomposition is: (I, B), (S, D), (I, O), (I, S, Q)

We can also write it as: (I, B), (S, D), (B, O), (I, S, Q)

Explanation:

The answer above is rendered in a very explanatory way.

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Phoenix [80]

Answer:

The right choice would be Option b (2.545).

Explanation:

The given values are:

The aggregate blend will be:

W_A = 55%

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W_ B = 25%

G_B = 2.331

W_C = 20%

G_C = 2.609

Now,

On applying the formula, we get

⇒ G_{BA}=\frac{W_A+W_B+W_C}{\frac{W_A}{G_A} +\frac{W_B}{G_B} +\frac{W_C}{G_C}}

On substituting the values, we get

⇒          =\frac{55+25+20}{\frac{55}{2.631} +\frac{25}{2.331} +\frac{20}{2.609}}

⇒          = \frac{100}{\frac{55}{2.631} +\frac{25}{2.331} +\frac{20}{2.609}}

⇒          =2.545

8 0
2 years ago
I want a problems and there solutions of The inception of cavitation?​
Ugo [173]

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The overview of the given scenario is explained in explanation segment below.

Explanation:

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How does a 2.5 MW wind turbine costing $ 4 million compare to a 5-kw wind turbine $3 /W? a) Same $/w b) Smaller $/w c) Larger $/
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Answer:

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Explanation:

hope helps

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The amount of phase shift between input and output signal is important when measuring ____ circuit​
svetoff [14.1K]

Answer:

The amount of phase shift between input and output signal is important when measuring a common emitter amplifier circuit​.

Explanation:

the amount of phase shift between input and output signal is important when measuring a common emitter amplifier circuit​

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