PL/SQL Collections

Question 1

Which collections allow holes?

Answer 1

AA, NT

Question 2

Which collections do not allow holes?

Answer 2

VA

Question 3

Which collections are empty at declaration?

Answer 3

AA

Question 4

Which collections are NULL at declaration?

Answer 4

NT, VA

Question 5

Which collections have a fixed capacity?

Answer 5

VA

Question 6

Which collections have a capacity that’s not set?

Answer 6

AA, NT

Question 7

What types of indexing do each collection have?

Answer 7

AA: Integers, Strings
NT: Integers
VA: Integers

Question 8

What is an associative array (AA)?

Answer 8

A set of key-value pairs where each key is unique and is used to locate the corresponding value

Question 9

What is the basic syntax of creating an AA?

Answer 9

TYPE type_name IS TABLE OF element_type INDEX BY index_type;

table_name type_name;

Question 10

What is the syntax for adding an element to an AA?

Answer 10

table_name(‘key’) := value;

Question 11

What is a nested table (NT)?

Answer 11

A one-dimensional array where the array size is dynamic

Question 12

What is the basic syntax of creating an NT?

Answer 12

TYPE type_name IS TABLE OF element_type;

table_name type_name;

Question 13

What is the syntax for adding elements to a NT?

Answer 13

table_name := type_name(‘elem1’, ‘elem2’);

Question 14

What are some of the collection methods PL/SQL provides for AA’s and NT’s?

Answer 14

• FIRST
• LAST
• PRIOR(i)
• NEXT(i)
• DELETE(i)
• COUNT
• EXISTS(I)
• EXTEND

Question 15

What does the FIRST function do?

Answer 15

Returns the index of the first element

Question 16

What does the LASTfunction do?

Answer 16

Returns the index of the last element

Question 17

What does the PRIOR(i)
function do?

Answer 17

Returns the index of the element that comes before index i

Question 18

What does the NEXT(i) function do?

Answer 18

Returns the index of the element that comes

after index i

Question 19

What does the DELETE(i) function do?

Answer 19

Deletes the element at index i

Question 20

What does the COUNT function do?

Answer 20

Returns the number of elements

Question 21

What does the EXISTS(i) function do?

Answer 21

Returns true/false if element i exists

Question 22

Which PL/SQL collection has sparse indexing?

Answer 22

AAs

Question 23

Which PL/SQL collection starts with dense indexing (at 1)?

Answer 23

NTs

Question 24

What does the EXTEND function do?

Answer 24

Appends one null element to a collection

Question 25

What is are Varrays?

Answer 25

A 1D array whose number of elements can vary from zero (empty) to the declared maximum size

Question 26

What is the basic syntax of creating a Varrays?

Answer 26

TYPE type_name IS VARRAY(size) OF element_type;

table_name type_name;

Question 27

What is the syntax for adding elements to a Varray?

Answer 27

table_name.EXTEND;

table_name (index) := value;