Lesson 2.4: Basics of the Relational Model Flashcards

1
Q

The relational model gives us a single way to represent data: as a two-dimensional table called a

A

relation.

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2
Q

The columns of a relation are named by

A

Attributes

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3
Q

attributes appear at the

A

top of the columns

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4
Q

The name of a relation and the set of attributes for a relation is called the ____ for that relation.

A

schema

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5
Q

The attributes in a relation schema are a ___, not a list.

A

set

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6
Q

In the relational model, a database consists of one or more relations. The set of schemas for the relations of a database is called a _____ or just a __________-

A

relational database schema, or just a database schema.

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7
Q

the rows of a relation, other than the header row containing the attribute names

A

tuples

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8
Q

We shall generally follow the convention that relation names begin with a _______, and attribute names begin with a ______.

A

capital letter

lower-case letter

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9
Q

t/f Relations are set of tuples, not lists of tuples

A

true

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10
Q

t/f it is not possible to reorder the attributes of the relation

A

false.

Moreover, we can reorder the attributes of the relation as we choose, without changing the relation.

However, when we reorder the relation schema, we must be careful to remember that the attributes are column headers.

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11
Q

t/f relations change over time

A

true

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12
Q

A set of attributes forms a key for a relation if we do not allow two tuples in a relation instance to have the same values in all the attributes of the key.

A

key constraints

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