Database Processing, 15e (Kroenke)
Chapter 6: Transforming Data Models into Database Designs
1) The first step in the database design process is to create tables and columns from entities and
attributes.
2) When creating a relational database design from E-R diagrams, first create a relation for each
relationship.
3) Each entity in the extended E-R model is represented as a table in the relational database
design.
4) An entity needs to be examined according to normalization criteria before creating a table
from it in the relational database design.
5) When creating a table in the relational database design from an entity in the extended E-R
model, the attributes of the entity become the rows of the table.
6) By default, the identifier of the entity becomes the foreign key of the corresponding table.
7) The ideal primary key is short, numeric, and fixed.
8) A surrogate key is appropriate when the primary key of a table contains a lengthy text field.
9) One of the important properties of an attribute is whether or not it is required.
10) A surrogate key is a unique, system-supplied identifier often used as the primary key of a
table.
11) The values of a surrogate key have no meaning to the users.
12) A surrogate key should be considered when the key contains a lengthy text field.
13) Deciding whether or not an attribute is required is determined during the data modeling
phase.
14) A null value is an attribute value that has been set to zero.
15) Data types are consistent across all DBMS products.
16) A default value is the value the user enters into the row the first time the user enters data.
17) A data constraint is a limitation on data values.
18) The last step in creating a table is to verify table normalization.
19) One of the important properties of a column is whether or not it can have a NULL value.
20) A foreign key is a key that does not belong in any table.
21) In a relational database design, all relationships are expressed by creating a foreign key.
22) When the key of one table is placed into a second table to represent a relationship, the key is
called a relational key in the second table.
23) To represent a 1:1 binary relationship in a relational database design, the key of one table is
placed into the second table.
24) When placing a foreign key for a 1:1 relationship, the key of either table can be used as the
foreign key in the other table.
25) In a 1:1 relationship, the foreign key is defined as an alternate key to make the DBMS
enforce uniqueness.
26) In a 1:N relationship, the term parent refers to the table on the “many” side of the
relationship.
27) In 1:N relationships, the table on the “one” side is called the parent.
28) In representing a 1:N relationship in a relational database design, the key of the table
representing the parent entity is placed as a foreign key in the table representing the child entity.
29) In representing a 1:N relationship in a relational database design, the key of the table
representing the entity on the “many” side is placed as a foreign key in the table representing the
entity on the “one” side of the relationship.
30) To represent a 1:N relationship in a relational database design, an intersection table is
created.
31) In 1:N relationships, the table on the “many” side is called the child.
32) To represent a one-to-many relationship in a relational database design, the key of the child
table is placed as a foreign key into the other table.
33) To represent an N:M relationship in a relational database design, a table is created between
the two tables to represent the relationship itself.
34) To represent an N:M relationship in a relational database design, an intersection table is
created.
35) To represent an N:M relationship in a relational database design, in essence it is reduced to
two 1:N relationships.
36) A key of an intersection table is always the combination of the keys of both parents.
37) In many-to-many relationships in a relational database design, the primary keys of both
tables are joined into a composite primary key in the intersection table.
38) An intersection table is always ID-dependent on both of its parent tables.
39) An intersection table can have additional attributes besides the keys of its parent tables.
40) Like all ID-dependent relationships, the parents of an association table are required.
41) Association tables sometimes connect more than two entities.
42) An ID-dependent table can be used to represent multivalued attributes.
43) All identifying relationships are 1:N.
44) When creating a table for an ID-dependent entity, both the key of the parent and the key of
the entity itself must appear in the table.
45) The design transformation for all IS-A relationships can be summarized by the phrase “place
the key of the parent table in the child table.”
46) When transforming an ID-dependent E-R data model relationship into a relational database
design where the child entity is designed to use a surrogate key, the relationship changes to a
weak but not ID-dependent relationship.
47) When transforming supertype/subtype entities into a relational database design, an entity is
created for the supertype only.
48) When transforming supertype/subtype entities into a relational database design, the key of
the supertype table is placed into the subtype table typically as the key.
49) To represent an IS-A relationship in a relational database design, the IS-A relationship must
be converted into a HAS-A relationship.
50) Discriminator attributes can be represented in relational designs.
51) When transforming supertype/subtype entities into a relational database design, all of the
attributes for the supertype table are placed into the subtype relations.
52) When transforming an extended E-R model into a relational database design, recursive
relationships are treated fundamentally the same as other HAS-A relationships.
53) Recursive M:N relationships are represented with an intersection table that shows pairs of
related rows from a single table.
54) Referential integrity constraints should disallow adding a new row to a child table when the
foreign key does not match a primary key value in the parent table.
55) A referential integrity constraint policy that insures foreign key values in a table are correctly
maintained when there is a change to the primary key value in the parent table is called a
cascading insertion.
56) A referential integrity constraint policy that insures that all rows containing a foreign key
value in a table are eliminated from the table when the row containing the corresponding primary
key value in a parent table is eliminated from the database is called cascading deletes.
57) When the parent entity is required (M) in a relationship, every row of the child table must
have a valid, non-null value of the foreign key.
58) Cascading deletions are generally not used with relationships between strong entities.
59) Cascading deletions are generally not used with relationships for weak child entities.
60) If the parent is required, then a new child row must be created with a valid foreign key value.
61) When the parent entity has a surrogate key, the enforcement actions are the same for both
parent and child.
62) When the child entity is required (M) in a relationship, there needs to always be at least one
child row for each parent row.
63) It is easy to enforce the referential integrity actions for N:M relationships.
64) Which of the following is not a step in the database design process?
A) Create tables and columns from entities and attributes
B) Select primary keys
C) Represent relationships
D) Create constraints and triggers