CS 3410 - Intro to Database Systems

A default value is the value the user enters into the row the first time the user enters data.

False

A foreign key is a key that does not belong in any table.

False

A null value is an attribute value that has been set to zero.

False

A referential integrity constraint policy that insures that 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 cascading insertions.

False

An entity needs to be examined according to normalization criteria before creating a table from it in the relational database design.

False

An intersection table can have additional attributes besides the keys of its parent tables.

False

By default, the identifier of the entity becomes the foreign key of the corresponding table.

False

Cascading deletions are generally not used with relationships for weak child entities.

False

Data types are consistent across all DBMS products.

False

Discriminator attributes can be represented in relational designs.

False

In a 1:N relationship, the term parent refers to the table on the 'many' side of the relationship.

False

In representing a 1:N relationship in a relational database design, the key of the table representing the entity of the 'many' side is placed as foreign key in the table representing the entity on the 'one' side of the relationship.

False

It is easy to enforce the referential integrity actions for M-M relationships.

False

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."

False

To represent a 1:N relationship in a relational database design, an intersection table is created.

False

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.

False

To represent an IS-A relationship in a relational database design, the IS-A relationship must be converted into a HAS-A relationship.

False

When creating a relational database design from E-R diagrams, first create a relation for each relationship.

False

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.

False

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.

False

When the parent entity has a surrogate key, the enforcement actions are the same for both parent and child.

False

When transforming supertype/subtype entities into a relational database design, all of the attributes for the supertype table are placed into the subtype relations.

False

When transforming supertype/subtype entities into a relational database design, an entity is created for the supertype only.

False

Whether or not an attribute is required is determined during the database modeling phase.

False

A data constraint is a limitation on data values.

True

A key of an intersection table is always the keys of both parents.

True

A referential integrity constraint policy that insures that all rows containing a particular 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.

True

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

True

A surrogate key is appropriate when the primary key of a table contains a lengthy text field.

True

A surrogate key should be considered when the key contains a lengthy text field.

True

All identifying relationships are 1:N.

True

An ID-dependent table can be used to represent multivalued attributes.

True

An association table sometimes connects more than two entities.

True

An intersection table is always ID-dependent on both of its parent tables.

True

Cascading deletions are generally not used with relationships between strong entities.

True

Each entity in the extended E-R model is represented as a table in the relational database design.

True

If the parent is required, then a new child row must be created with a valid foreign key value.

True

In 1:N relationships, the table on the 'many' side is called the child.

True

In a 1:1 relationship, the foreign key is defined as an alternate key to make the DBMS enforce uniqueness.

True

In a 1:N relationship, the table on the 'one' side is called the parent.

True

In a many-to-many relationship in a relational database design, the primary keys of both tables are joined into a composite primary key in the intersection table.

True

In a relational database design, all relationships are expressed by creating a foreign key.

True

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.

True

Like all ID-dependent relationships, the parents of an association table are required.

True

One advantage of using the CONSTRAINT command to define a primary key is that the database designer controls the name of the constraint.

True

One of the important properties of a column is whether or not it can have a NULL value.

True

One of the important properties of an attribute is whether or not it is required.

True

Recursive M:N relationships are represented with an intersection table that shows pairs of related rows from a single table.

True

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.

True

The SQL CREATE TABLE statement is used to name a new table and describe the table's columns.

True

The SQL keyword CONSTRAINT can be used in conjunction with the SQL keywords PRIMARY KEY and FOREIGN KEY.

True

The SQL keyword CONSTRAINT is used to define one of several types of constraints.

True

The SQL keyword CONSTRAINT is used to limit the column values to specific values.

True

The SQL keyword PRIMARY KEY is used to designate the column(s) that are the primary key for the table.

True

The SQL keyword UNIQUE is used to define alternate keys.

True

The first step in the database design process is to create tables and columns from entities and attributes.

True

The ideal primary key is short, numeric, and fixed.

True

The last step in creating a table is to verify table normalization.

True

The values of a surrogate key have no meaning to the users.

True

To represent a 1:1 binary relationship in a relational database design, the key of one table is placed into the second table.

True

To represent an N:M relationship in a relational database design, a table is created to represent the relationship itself.

True

To represent an N:M relationship in a relational database design, an intersection table is created.

True

To represent an N:M relationship in a relational database design, in essence it is reduced to two 1:N relationships.

True

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.

True

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.

True

When the child entity is required (M) in a relationship, there needs to be at least one child row for each parent row at all times.

True

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.

True

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.

True

When transforming an extended E-R model into a relational database design, recursive relationships are treated fundamentally the same as other HAS-A relationships.

True

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.

True

In many-to-many relationships between strong entities in a relational database design, which of the following is not true? A) The intersection table is ID-dependent on one of the parents B) The intersection table is ID-dependent on both of the parents C) The relationships from the intersection table to the parent tables are identifying relationships D) The maximum cardinality to the intersection table is always N

A) The intersection table is ID-dependent on one of the parents.

Which of the following is not true for an ideal primary key? A) a composite of several long attributes B) numeric C) fixed D) short

A) a composite of several long attributes

Each attribute of an entity becomes a(n) ________ of a table. A) column B) primary key C) foreign key D) alternate key

A) column

When transforming an ID-dependent E-R data model relationship into a relational database design, the referential integrity constraints should allow ________. A) parent updates to cascade B) child updates to cascade C) child deletes to cascade D) Both A and B are correct

A) parent updates to cascade

The identifier of the entity becomes the ________ of the corresponding table. A) primary key B) foreign key C) supertype D) subtype

A) primary key

The binary constraint MUST COVER indicates that ________. A) a specific binary relationship must be included in a ternary relationship B) a binary relationship includes a set of value combinations that must all occur in a ternary relationship C) a table includes values that must occur in a binary relationship D) a table includes values that must occur in a ternary relationship

B) a binary relationship includes a set of value combinations that must all occur in a ternary relationship

In a relational database design, all relationships are expressed by ________. A) creating a primary key B) creating a foreign key C) creating a supertype D) creating a subtype

B) creating a foreign key

When representing a 1:1 relationship in a relational database design, ________. A) the key of each table must be placed as foreign keys into the other B) the key of either table may be placed as a foreign key into the other C) the key of both tables must be the same D) the intersection table gets the key from both relations

B) the key of either table may be placed as a foreign key into the other

To represent a one-to-many relationship in a relational database design, ________. A) the key of the child is placed as a foreign key into the parent B) the key of the parent is placed as a foreign key into the child C) an intersection table must be created D) the key of the table on the "many" side is placed in the table on the "one" side

B) the key of the parent is placed as a foreign key into the child

Which of the following is not true about a NULL attribute? A) On insertion, entering the data for that field is optional. B) It is an important property of an attribute. C) It must have a default value specified. D) A primary key can't be NULL.

C) It must have a default value specified.

A surrogate key should be considered when ________. A) A relationship is N:M B) A composite key is required C) The key contains a lengthy text field D) The key contains a number

C) The key contains a lengthy text field

Which of the following is not true about surrogate keys? A) They are identifiers that are supplied by the system, not the users. B) They have no meaning to the users. C) They are non-unique within a table. D) They can be problematic when combining databases.

C) They are non-unique within a table.

A referential integrity constraint policy that insures that 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) incremental updates B) incremental deletes C) cascading updates D) cascading deletes

C) cascading updates

The first step in transforming an extended E-R model into a relational database design is to ________. A) create a table for each relationship B) evaluate the entities against the normalization criteria C) create a table for each entity D) remove any recursive relationships

C) create a table for each entity

In relational database design, ID-dependent entities are not used to ________. A) represent N:M relationships B) handle associative relationships C) represent relationships where the child identifier does not include the key of the parent D) handle archetype/instance relationships

C) represent relationships where the child identifier does not include the key of the parent

In many-to-many relationships in a relational database design, ________. A) the key of the child is placed as a foreign key into the parent B) the key of the parent is placed as a foreign key into the child C) the keys of both tables are placed in a third table D) the keys of both entity tables are placed in each other

C) the keys of both tables are placed in a third table

A referential integrity constraint policy that guarantees that a row in a parent table always has a required entry in a child table ________. A) is known as a minimum cardinality enforcement action B) needs to be documented by the database development team C) is enforced in most DBMS products D) Both A and B are correct

D) Both A and B are correct

For the M-O (parent mandatory, child optional) case, what action(s) should be taken to ensure minimum cardinality is maintained? A) Define referential integrity constraint from child to parent B) Make foreign key NOT NULL C) Will require trigger or other application code D) Both A and B are correct

D) Both A and B are correct

In a supertype-subtype structure, discriminator attributes ________. A) are easily represented in a relational design B) cannot be represented in a relational design C) require application logic to determine which subtypes correspond to a specific supertype instance D) Both B and C are correct

D) Both B and C are correct

Which of the following is not true about N:M recursive relationships? A) Both foreign keys in the intersection table refer to the same table. B) Since it is a recursive relationship, an intersection table is not needed. C) The foreign keys in the intersection table can't refer to the same attribute in the parent table. D) Both B and C are correct.

D) Both B and C are correct.

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

D) Create constraints and triggers

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.

D) When the relationship is 1:N, a new table must be defined to represent the relationship.

The binary constraint MUST NOT indicates that ________. A) a specific binary relationship must not be included in a ternary relationship B) a table includes values that must not occur in a binary relationship C) a table includes values that must not occur in a ternary relationship D) a binary relationship includes value combinations that must not occur in a ternary relationship

D) a binary relationship includes value combinations that must not occur in a ternary relationship

Many-to-many relationships are represented by ________. A) two tables with an M:N relationship B) two tables with a 1:N relationship C) an intersection table which has M:N relationships with the two tables D) an intersection table which has 1:N relationships with the two tables

D) an intersection table which has 1:N relationships with the two tables

A referential integrity constraint policy that insures that all rows containing a particular 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 ________. A) incremental updates B) incremental deletes C) cascading updates D) cascading deletes

D) cascading deletes

When transforming an ID-dependent E-R data model relationship into a relational database design and the parent entity has a surrogate primary key and the child entity has a data identifier, then the primary key of the child table should be ________. A) the parent's surrogate key + the child's data key B) the parent's surrogate key + a surrogate key in the child C) either A or B will work, but method A is preferable D) either A or B will work, but method B is preferable

D) either A or B will work, but method B is preferable

When representing a one-to-many relationship in a relational database design, ________. A) the parent is always on the one side of the "one-to-many" relationship B) the child is always on the one side of the "one-to-many" relationship C) either parent or child can be on the one side of the "one-to-many" relationship, and the choice is arbitrary D) either parent or child can be on the one side of the "one-to-many" relationship, and special criteria indicate which table should be on the one side

A) the parent is always on the one side of the "one-to-many" relationship

When transforming an E-R data model into a relational database design, the key of the parent entity should be placed as part of the primary key into the child entity ________. A) when the child entity is ID-dependent B) when the child entity is non-ID-dependent C) when the child entity has a 1:1 relationship with the parent entity D) when the child entity has a 1:N relationship with the parent entity

A) when the child entity is ID-dependent

Which of the following is not true about representing subtypes in a relational database design? A) One table is created for the supertype and one for each subtype. B) All of the attributes of the supertype are added to the subtype relations. C) The key of the supertype is made the key of the subtypes. D) An instance of the supertype may be related to one instance each of several subtypes.

B) All of the attributes of the supertype are added to the subtype relations.

Which of the following is not true of the MUST constraint? A) It may be needed in ternary relationships to enforce special business rules. B) It can be expressed directly in a relational model. C) It must be enforced by program code. D) It requires that one entity be combined with another entity.

B) It can be expressed directly in a relational model.