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