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Question
Which of the following is not true of recursive relationships?A) When the recursive relationship is M:N, an intersection table is created.
B) The rows of a single table can play two different roles.
C) Recursive relationships can be 1:1, 1:N, or M:N relationships.
D) When the relationship is 1:N, a new table must be defined to represent the relationship.
Answer
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Related questions
Q:
Suppose you have created a data model for an airline based on a variety of forms, reports, user interviews, data sources, etc. Your client comes forward with a new desired report that includes passenger weights and a relationship between passengers and employees, neither of which is in your E-R diagram. You should ________.
A) create a new, separate E-R diagram with just the new information
B) add the relationship and the weight attribute to the existing data model
C) add the relationship but not the weight attribute
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C) Subtypes are used to avoid a situation in which some attributes are required to be null.
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Subtypes can be exclusive or inclusive.
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All weak entities must have a minimum cardinality of 1 on the entity on which it depends.
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ID-dependent entities are a common type of weak entity.
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An entity that represents something that can exist on its own is called a strong entity.
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In an E-R model, the three types of minimum cardinality are mandatory, optional, and indeterminate.
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In a 1:N relationship, the term parent refers to the N side of the relationship.
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Relationships are classified by their cardinality.
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In today's E-R models, attributes of relationships are still used.
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Q:
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A) IS
B) IS NOT
C) IS NULL
D) COUNT(NULL)
Q:
When a table is created using existing data from multiple sources, you are likely to find that the different sources code data in slightly different ways. This is an example of ________.
A) the multivalued, multicolumn problem
B) the inconsistent values problem
C) the missing values problem
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Q:
A classic example of unneeded normalization is when we are dealing with ________.
A) ZIP codes
B) sales orders and line items
C) association patterns
D) multivalued dependencies
Q:
The SQL keyword TOP ________.
A) limits the number of columns retrieved from a table
B) limits the number of rows retrieved from a table
C) limits the number of tables retrieved from a database
D) A and C
Q:
During the second step of assessing table structure, you are trying to determine ________.
A) relationships
B) candidate keys
C) updatability
D) efficiency
Q:
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A) counting rows
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Q:
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