In a PL/SQL block, how can you programmatically check whether a cursor is currently open before using it?

Introduction / Context:
This question tests your understanding of cursor attributes in Oracle PL/SQL. When working with explicit cursors, it is often necessary to know whether a cursor is open before attempting operations such as FETCH or CLOSE. Oracle provides special attributes that expose the state of a cursor. Knowing which attribute to use is a common interview point and is important for writing robust, error free PL/SQL code.

Given Data / Assumptions:
• The environment is Oracle PL/SQL and we are dealing with an explicit cursor named cursor_name. • We want to determine whether this cursor is currently open inside the PL/SQL block. • We assume knowledge of common cursor attributes such as %ISOPEN, %FOUND, and %NOTFOUND. • No numeric calculations are involved; only understanding of attributes and their purpose is required.

Concept / Approach:
Oracle PL/SQL defines four standard attributes for explicit cursors: %ISOPEN, %FOUND, %NOTFOUND, and %ROWCOUNT. The attribute %ISOPEN returns TRUE if the cursor is currently open and FALSE otherwise. This attribute is specifically designed to let you check the cursor state before performing operations that require it to be open. The other attributes describe fetch results or the number of rows processed and are only valid when the cursor is already open. The correct answer must explicitly reference %ISOPEN as the Boolean check for cursor openness.

Step-by-Step Solution:
Step 1: Recall that explicit cursors in PL/SQL have attributes that provide status information. Step 2: Identify %ISOPEN as the attribute whose sole purpose is to indicate whether the cursor is open. Step 3: Understand that this attribute returns a Boolean value and can be used directly in an IF statement. Step 4: Recognize that querying data dictionary views or session views is not the standard way to check cursor state in PL/SQL code. Step 5: Choose the option that mentions checking cursor_name%ISOPEN within the PL/SQL block.

Verification / Alternative check:
Consider a simple code fragment. You declare a cursor and then write IF NOT cursor_name%ISOPEN THEN OPEN cursor_name; END IF;. This pattern is widely used in PL/SQL examples and documentation. It directly illustrates that %ISOPEN is the attribute that reports whether the cursor has been opened. Using %FOUND or %NOTFOUND would not make sense before the first FETCH. Also, relying on SQLCODE or system views would be unnecessarily complex and not specific to cursor state. This reasoning confirms that the attribute %ISOPEN is the correct mechanism.

Why Other Options Are Wrong:
Option b suggests querying data dictionary views like USER_TABLES, which provide information about tables, not the runtime state of PL/SQL cursors. Option c uses cursor_name%FOUND, which only indicates whether the last fetch returned a row and assumes the cursor is already open. Option d refers to v$session, a dynamic performance view for sessions, which does not expose simple Boolean flags for each explicit cursor in PL/SQL code. Option e relies on SQLCODE, which is a general error code for the last SQL operation but does not directly indicate whether a cursor is open.

Common Pitfalls:
A common mistake is to forget to open a cursor before fetching, leading to cursor related exceptions. Using %ISOPEN helps guard against this by allowing conditional opens. Another pitfall is misusing %FOUND or %NOTFOUND to infer whether a cursor is open, which can lead to undefined behavior if the cursor has not been opened or fetched from yet. Developers should also remember that cursor attributes are only meaningful within the scope of the PL/SQL block that declares the cursor and cannot be inspected from outside that scope using simple SQL queries.

Final Answer:
The correct choice is By checking the Boolean attribute cursor_name%ISOPEN inside the PL/SQL block., because %ISOPEN is the standard PL/SQL attribute provided specifically to report whether an explicit cursor is currently open.