[Chapter 8] PLVtab: Easy Access to PL/SQL Tables Chapter 8 8. PLVtab: Easy Access to PL/SQL TablesContents:Using PLVtab-Based PL/SQL Table TypesDisplaying PLVtab TablesShowing Header ToggleShowing Row Number ToggleSetting the Display PrefixEmptying Tables with PLVtabImplementing PLVtab.displayThe PLVtab (PL/Vision TABle) package 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:Show or suppress a header for the tableShow or suppress the row numbers for the table valuesDisplay a prefix before each row of the tableThis chapter shows how to use the different aspects of PLVtab.8.1 Using PLVtab-Based PL/SQL Table TypesWhen 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: Table 8.1: Table Types Predefined in PLVtab TypeDescription boolean_table PL/SQL table of Booleans date_table PL/SQL table of dates integer_table PL/SQL table of integers number_table PL/SQL table of numbers vc30_table PL/SQL table of VARCHAR2(30) strings vc60_table PL/SQL table of VARCHAR2(60) strings vc80_table PL/SQL table of VARCHAR2(80) strings vc2000_table PL/SQL table of VARCHAR2(2000) strings ident_table PL/SQL table of VARCHAR2(100) strings; matches PLV.plsql_identifier declaration. vcmax_table PL/SQL table of VARCHAR2(32767) stringsLet'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; BEGINWith the PLVtab package in place, all I have to is the following:DECLARE yesno_tab PLVtab.boolean_table; BEGINOnce you have declared a table using PLVtab, you manipulate that table as you would a table based on your own table TYPE statement. 7.4 Controlling Output from p8.2 Displaying PLVtab Tables Copyright (c) 2000 O'Reilly & Associates. All rights reserved.