Practice exercise

1. Which two statements are true about associative arrays?

   1. Associative arrays can have negative subscripts.

   2. Associative arrays are always dense collections.

   3. Associative arrays don't need initialization in a PL/SQL block.

   4. The upper limit of associative arrays can be dynamically modified.

2. Which of the following statements is true about nested tables?

   1. Nested tables are stored in a segment different from that of the parent table.

   2. Nested table columns can have string subscripts

   3. Nested tables can grow dynamically up to any extent.

   4. A database column of the nested table collection type can be separately queried by its storage name.

3. Only varrays can have sequential numbers as subscripts.

   1. True

   2. False

4. Which of the following associative array declarations is/are correct?

   DECLARE
   TYPE T1 IS TABLE OF NUMBER INDEX BY BOOLEAN;
   TYPE T2 IS TABLE OF VARCHAR2(10) INDEX BY NUMBER;
   TYPE T3 IS TABLE OF DATE INDEX BY SIGNTYPE;
   TYPE T4 IS TABLE OF EMPLOYEES%ROWTYPE INDEX BY POSITIVE;
   BEGIN
   …
   …
   END;

   1. T1

   2. T2

   3. T3

   4. T4...