define UNIQUE and NON-UNIQUE indexes for relations.
Computer Networking: A Top-Down Approach (7th Edition)
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Author:James Kurose, Keith Ross
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Given the Relational Model Notation below, extend it to define
UNIQUE and NON-UNIQUE indexes for relations.
![Given the Relational Model Notation below (in pages 156-157 of your book), extend it to define
UNIQUE and NON-UNIQUE indexes for relations.
5.1.3 Relational Model Notation
We will use the following notation in our presentation:
- A relation schema R of degree n is denoted by R(Aj, Az, . , A,).
....
The uppercase letters Q, R, S denote relation names.
The lowercase letters q, r, s denote relation states.
- The letters t, u, v denote tuples.
- In general, the name of a relation schema such as STUDENT also indicates
the current set of tuples in that relation-the current relation state-whereas
STUDENT(Name, Ssn, ...) refers only to the relation schema.
- An attribute A can be qualified with the relation name R to which it belongs
by using the dot notation R.A-for example, STUDENT.Name or
STUDENT.Age. This is because the same name may be used for two attri-
butes in different relations. However, all attribute names in a particular
relation must be distinct.
- An n-tuple t in a relation r(R) is denoted by t = <v, v½. ... , V>, where v, is
the value corresponding to attribute A. The following notation refers to
component values of tuples:
o Both t[A,] and t.A; (and sometimes f[i]) refer to the value v, in t for attri-
bute A-
- Both t[A, A ., A-] and t.(A, An .., A-), where A, Ap .. , A, is a list
of attributes from R, refer to the subtuple of values <v, Vws . , v> from t
corresponding to the attributes specified in the list.
As an example, consider the tuple t = <'Barbara Benson', '533-69-1238',
(817)839-8461', '7384 Fontana Lane', NULL, 19, 3.25> from the STUDENT relation in Fig-
ure 5.1; we have f[Name] = <'Barbara Benson'>, and t[Ssn, Gpa, Age] = <533-69-1238',
3.25, 19>.](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2Fe2d8fcbe-3030-49bd-9137-48407013268d%2Fb7948b4e-59e6-4595-92d8-6399e296f150%2Fuvfylq_processed.png&w=3840&q=75)
Transcribed Image Text:Given the Relational Model Notation below (in pages 156-157 of your book), extend it to define
UNIQUE and NON-UNIQUE indexes for relations.
5.1.3 Relational Model Notation
We will use the following notation in our presentation:
- A relation schema R of degree n is denoted by R(Aj, Az, . , A,).
....
The uppercase letters Q, R, S denote relation names.
The lowercase letters q, r, s denote relation states.
- The letters t, u, v denote tuples.
- In general, the name of a relation schema such as STUDENT also indicates
the current set of tuples in that relation-the current relation state-whereas
STUDENT(Name, Ssn, ...) refers only to the relation schema.
- An attribute A can be qualified with the relation name R to which it belongs
by using the dot notation R.A-for example, STUDENT.Name or
STUDENT.Age. This is because the same name may be used for two attri-
butes in different relations. However, all attribute names in a particular
relation must be distinct.
- An n-tuple t in a relation r(R) is denoted by t = <v, v½. ... , V>, where v, is
the value corresponding to attribute A. The following notation refers to
component values of tuples:
o Both t[A,] and t.A; (and sometimes f[i]) refer to the value v, in t for attri-
bute A-
- Both t[A, A ., A-] and t.(A, An .., A-), where A, Ap .. , A, is a list
of attributes from R, refer to the subtuple of values <v, Vws . , v> from t
corresponding to the attributes specified in the list.
As an example, consider the tuple t = <'Barbara Benson', '533-69-1238',
(817)839-8461', '7384 Fontana Lane', NULL, 19, 3.25> from the STUDENT relation in Fig-
ure 5.1; we have f[Name] = <'Barbara Benson'>, and t[Ssn, Gpa, Age] = <533-69-1238',
3.25, 19>.
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