The PLVtab (PL/Vision TABle) packag e offers predefined PL/SQL table types and programs to make it easier to declare, use, and display the contents of PL/SQL tables. PL/SQL tables are the closest things to arrays in PL/SQL , but there are a number of complications. First, to use a PL/SQL table, you first have to declare a table type. Then you can declare and use the PL/SQL table itself. Beyond the definition of the PL/SQL table, the fact that it is a sparse, unbounded, homogeneous data structure can lead to complications, particularly when it comes to scanning and displaying those structures (see Chapter 10 of Oracle PL/SQL Programming ).
By using PLVtab, you can avoid (in most cases) having to define your own PL/SQL table types. You can also take advantage of flexible, powerful display procedures to view table contents.
When you display the contents of PL/SQL tables, PLVtab allows you to:
This chapter shows how to use the different aspects of PLVtab.
When you use PL/SQL tables, you normally perform a number of common actions, including defining the table type, declaring the table, filling up the rows, referencing the rows, and emptying the table when done. When using a PLVtab-based table, you do not have to declare the table type. Instead you simply reference the package-based type in your declaration. PLVtab predefines the following PL/SQL table TYPEs, shown in Table 8.1 :
Let's compare the "native" and PL/Vision approaches to defining PL/SQL tables. In the following anonymous block, I define a PL/SQL table of Booleans without the assistance of PLVtab .
DECLARE TYPE bool_tabtype IS TABLE OF BOOLEAN INDEX BY BINARY_INTEGER; yesno_tab bool_tabtype; BEGIN
With the PLVtab package in place, all I have to is the following:
DECLARE yesno_tab PLVtab.boolean_table; BEGIN
Once you have declared a table using PLVtab, you manipulate that table as you would a table based on your own table TYPE statement.
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