Q&A Hero

Q: SQL views can be used to provide a level of insulation between data processed by applications and the data actually stored in the database tables.

Q: SQL views can be used to hide columns.

Q: The values in an SQL view are not always changeable through the view itself.

Q: The SQL command SELECT is used to retrieve view instances.

Q: According to the SQL-92 standard, statements used to construct views cannot contain the WHERE clause.

Q: SQL views are constructed from SELECT statements.

Q: The SQL command CREATE USER VIEW is used to create a virtual table.

Q: An SQL virtual table is called a view.

Q: Rows can be removed from a table by using the SQL DELETE statement.

Q: The SQL keyword MODIFY is used to change a column value.

Q: The SQL SET keyword is used to specify a new value when changing a column value.

Q: Rows in a table can be changed by using the SQL UPDATE statement.

Q: Unless it is being used to copy data from one table to another, the SQL INSERT statement can be used to insert only a single row into a table.

Q: One or more rows can be added to a table by using the SQL INSERT statement.

Q: When the correct SQL command is used to delete a table's structure, the command can only be used with a table that has already had its data removed.

Q: The SQL keyword DELETE is used to delete a table's structure.

Q: Data values to be added to a table are specified by using the SQL VALUES clause.

Q: The SQL keyword MODIFY is used to change the structure, properties or constraints of a table.

Q: The SQL keyword CHECK is used to limit column values to specific values.

Q: If the table ITEM has a column WEIGHT, and WEIGHT has the data type Numeric (4,2), the value 4321 will be displayed by the DBMS as 43.21.

Q: If the table PRODUCT has a column PRICE, and PRICE has the data type Numeric (8,2), the value 98765 stored in that field will be displayed by the DBMS as 98765.00.

Q: The SQL keyword UNIQUE is used to define alternate keys.

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

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

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

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

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

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

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

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

Q: Using the VRG database as an example, briefly describe what a final database design consists of.

Q: What are the four sets of minimum cardinalities that can be present in a 1:N binary relationship?

Q: Write the database table design to represent the data model below, including tables, the proper placement of the foreign key, and referential integrity constraint.

Q: What are MUST NOT and MUST COVER constraints?

Q: What is an association relationship and how does it differ from an N:M relationship?

Q: Explain the representation of a many-to-many strong entity relationship in a relational database design.

Q: Explain the representation of a one-to-many strong entity relationship in a relational database design.

Q: How are one-to-one recursive relationships addressed using the relational model?

Q: Explain the pragmatic reason for using surrogate keys.

Q: Briefly describe the process of converting an extended E-R model into a relational database design.

Q: 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

Q: 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

Q: 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

Q: 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

Q: 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

Q: 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

Q: 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

Q: Which of the following is not true of 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.

Q: 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.

Q: 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

Q: 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.

Q: 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.

Q: 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

Q: 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

Q: 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

Q: 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

Q: 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

Q: 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

Q: 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

Q: 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

Q: 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

Q: 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

Q: 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.

Q: 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.

Q: 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

Q: 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

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

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

Q: 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

Q: 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

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

Q: 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.

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

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

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

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

Q: 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.

Q: 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.

Q: 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.

Q: 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.