Chapter 5

false

A UNIQUE constraint is a column-level constraint. True False

true

A database trigger can let you constrain or restrict column-level, row-level, and table-level behaviors. True False

false

A single NOT NULL constraint can apply to more than one column at a time. True False

false

Foreign key constraints implement NOT NULL constraints. True False

enum, set

In MySQL, which data types mimic the check constraint? (multiple answer) SET FLOAT ENUM BLOB CLOB

false

In Oracle a unique index is indistinguishable from a UNIQUE constraint. True False

false

In Oracle, unique indexes can only be created by creating a UNIQUE constraint. True False

true

In Oracle, when no UNIQUE constraint is dependent on the unique index, you can drop or remove those indexes without modifying the table the indexes organize. True False

collection, 0..*

In an Oracle database, an unconstrained column that has no upward limit on the number of values holds a ______________, which typically has ____ cardinality (multiple answers possible). Collection, 0..* Set, 1..* Set, 0..* Enum, 0..1 Collection, 1..*

false

In both Oracle and MySQL, you can give primary key constraints unique names. True False

false

NOT NULL constraints can only be implemented out-of-line. True False

true

Referential integrity constraints ensure that references between tables can be found. True False

true

Referential integrity ensures that foreign key values are found in the list of valid primary key values. True False

all_constraints, user_constraints, dba_constraints

UNIQUE constraints are visible in which administrative view(s) (multiple answers possible): USER_IND_COLUMNS ALL_CONSTRAINTS USER_CONSTRAINTS USER_CONS_COLUMNS DBA_CONSTRAINTS

true

UNIQUE constraints must be added out-of-line when creating a table or must be added using an ALTER TABLE statement. True False

a, c, e

What are the possible implementations of foreign keys in Oracle? (multiple answers possible) Prevent the updating or deleting of a primary key value when a foreign key holds a copy of that value Allow the updating of the foreign key value to a value not found in the list of values within the primary key column Allow the updating of the foreign key value to a null value when the row containing the primary key is deleted None of the above Allow the deleting of a row without updating the primary key values

surrogate key, natural key

What unique keys should every well-designed table have? (multiple answers possible) Surrogate key Primary key Foreign key Natural key

false

When applied to a column in a table, the ENUM data type limits a column to a list of 64 possible string values. True False

true

When applied to a column in a table, the ENUM data type lists the possible elements in a set and requires that any insert or update to the column be found in that list. True False

true

When connecting a primary key and a foreign key, both keys must use the same number of columns and contain the same column data types. True False

1..1

column's default cardinality is _______ when is has a NOT NULL constraint (multiple answers possible). 0..1 None of the above 1..* 1..1 0..*

true

Cardinality means the number of elements in a set. True False

B, E

Column-level constraints let you restrict (multiple answers possible): the behavior of one or a group of column values in the same row whether a column contains values or not none of the above the value list of a column to those found in another column what values can be inserted into a column

true

Table-level constraints restrict the behavior between rows in a table. True False

false

You can drop an UNIQUE INDEX created by a UNIQUE constraint. True False

true

You can implement column constraints in-line when the column is made or out-of-line after the column is created in a table. True False

true

You forgot to create the appropriate NOT NULL constraint when you made the table so you must use an ALTER TABLE statement to add this constraint to the appropriate table column. True False

natural keys, surrogate keys

______________ are candidate keys. (multiple answers possible) Natural keys Super keys Foreign keys Surrogate keys Primary keys

check

_______________ constraint(s) allows you to verify the value of a column during the insert or update through the use of a qualified boundary in an Oracle database. (multiple answers possible) Not Null Foreign Key Unique Check Primary Key

surrogate keys

________________ are ID columns that are generally populated with the results from automatic numbering structures (multiple answers possible). None of the above Super keys Surrogate keys Natural keys Foreign keys