When a debug action interrupts program execution, the PL/SQL Interpreter takes control and establishes what is known as a debug level. At a debug level, you can enter commands and PL/SQL statements to inspect and modify the state of the interrupted program unit as well as resume execution.
Since any PL/SQL code interactively entered at a debug level may itself be interrupted (for example, by encountering another breakpoint), it is possible for debug levels to nest. To facilitate distinguishing one debug level from another, the levels are numbered. The most deeply nested level is assigned the highest number. Numbering starts at zero with the outermost level.
The 0th or outermost level is commonly referred to as top level. Top level has no associated program state since it is the outermost level at which program units are originally invoked. When code invoked from top level is interrupted, debug level 1 is established. Similarly, interrupting code invoked from debug level 1 establishes debug level 2, and so on.
The PL/SQL Interpreter command prompt reflects the current debug level. When the PL/SQL Interpreter enters levels below top level, the prompt includes a prefix containing the current debug level number. For example, the PL/SQL Interpreter command prompt at debug level 1 appears as:
(debug 1)PL/SQL>
About the current scope location
About the current execution location
Copyright © 1984, 2005, Oracle. All rights reserved.