Chapter 6: Database Design Using Entity-Relationship Models
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1.  

When a key of one relation is stored in a second relation, it is called a foreign key.

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2.  

A tree is a data structure in which the elements of the structure have only one-to-many relationships with one another.

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3.  

Every node of a tree has a parent.

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4.  

The descendants of a node are called children.

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5.  

Nodes having the same parent are called siblings.

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6.  

In a tree every node has, at most, one parent.

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7.  

A simple network is a data structure of elements having only one-to-many relationships.

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8.  

In a simple network, all elements have exactly one parent.

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9.  

A complex network is a data structure of elements in which at least one of the relationships is many-to-many.

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10.  

A bill of materials is a special data structure that occurs frequently in manufacturing applications.

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11.  

A surrogate key is a unique, system supplied identifier used as the primary key of a relation.

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12.  

A null value is an attribute value that has never been supplied.

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13.  

To represent a one-to-many relationship, we place the key of the parent into the child.

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14.  

To represent a many-to-many relationship, we create an intersection relation that contains the keys of the other two relations.

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15.  

Recursive relationships are relationships in which the participants in the relationship arise from the same entity class.

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16.  

For a many-to-many recursion, we create an intersection table that represents the many-to-many relationship.

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17.  

Ternary and higher-order relationships can be treated as combinations of binary relationships.

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18.  

The problem with null values is that they are ambiguous.

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19.  

There are three types of recursive relationships; one-to-one, one-to-many, and many-to many.

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20.  

The key for an intersection relation is always the combination of parent keys.

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