Chapter 6. Index-by Tables
Oracle8 introduced the term collection to describe three new datatypes: index-by tables, nested tables, and variable arrays. These collections are quite similar and are really just conceptual riffs on the old PL/SQL table. We’ll examine each of these new types in the next three chapters.
The index-by table (or the structure formerly known as a PL/SQL table) is PL/SQL’s answer to an array. Like an array, an index-by table consists of homogeneous elements (meaning that all the elements have the same datatype) that are indexed by an integer (hence the name index-by table). Unlike arrays in other languages, PL/SQL index-by tables are one-dimensional, sparse (meaning that there can be “gaps” between elements), and unconstrained (meaning that the number of elements can grow). This chapter tests your understanding of these extremely useful structures.
Beginner
6-1. | What two steps are required before you can work with an index-by table? |
6-2. | Can index-by tables be declared with indexes other than BINARY_INTEGERs? |
6-3. | Consider this definition of an index-by table TYPE: DECLARE TYPE number_tabtype IS TABLE OF NUMBER INDEX BY BINARY_INTEGER; Which of the following index-by table declarations is valid?
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6-4. | Consider this definition of an index-by table TYPE and table: DECLARE TYPE number_tabtype IS TABLE OF NUMBER INDEX BY BINARY_INTEGER; acres_clearcut number_tabtype; Which of the following ... |
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