Implicit Cursor Life Cycle FAQS

1. What is an implicit cursor in Oracle?

An implicit cursor is automatically created and managed by Oracle whenever a DML statement (INSERT, UPDATE, DELETE) or a single-row SELECT INTO statement is executed.

• No need to explicitly declare, open, fetch, or close.
• Oracle internally handles the cursor’s life cycle.

2. What are the steps in the life cycle of an implicit cursor?

The implicit cursor life cycle has three main stages:

Stage	Description
Creation & Parsing	Oracle creates the cursor in memory and parses the SQL statement.
Execution & Fetching	SQL statement is executed. For SELECT INTO, data is fetched into variables. For DML, rows are affected.
Closing	Cursor is automatically closed once statement execution completes.

✅ Implicit cursors are automatically closed by Oracle; you don’t need to close them manually.

3. Life cycle example with a DML statement

BEGIN

   UPDATE employees

   SET salary = salary * 1.10

   WHERE department_id = 50;

   DBMS_OUTPUT.PUT_LINE(SQL%ROWCOUNT || ' rows updated.');

END;

Life Cycle Steps:

1.    Creation & Parsing – Oracle creates the implicit cursor for the UPDATE.

2.    Execution & Fetching – Statement runs, rows updated, SQL%ROWCOUNT is set.

3.    Closing – Oracle automatically closes the cursor after execution.

4. Can an implicit cursor be reused?

• No, each implicit cursor is tied to a single SQL statement.
• Each new SQL statement creates a new implicit cursor.

UPDATE employees SET salary = salary * 1.1 WHERE department_id = 10;

DBMS_OUTPUT.PUT_LINE(SQL%ROWCOUNT);

UPDATE employees SET salary = salary * 1.05 WHERE department_id = 20;

DBMS_OUTPUT.PUT_LINE(SQL%ROWCOUNT);

• Two implicit cursors are created here, one for each UPDATE.

5. Attributes of an implicit cursor during its life cycle

Attribute	Description	When Valid
SQL%FOUND	TRUE if at least one row affected	After execution
SQL%NOTFOUND	TRUE if no rows affected	After execution
SQL%ROWCOUNT	Number of rows affected/fetched	After execution
SQL%ISOPEN	Always FALSE	Implicit cursors auto-close

❌ %ISOPEN is always FALSE because implicit cursors do not stay open after execution.

6. Life cycle differences: SELECT INTO vs DML

Type	Execution Stage	Fetching	Closing
SELECT INTO	SQL parsed and executed	Data fetched into variables	Cursor auto-closes
DML (INSERT/UPDATE/DELETE)	SQL parsed and executed	Rows affected	Cursor auto-closes

7. What happens if a SELECT INTO returns no rows?

• Oracle raises NO_DATA_FOUND exception.
• The implicit cursor still completes its life cycle and closes automatically.

8. What happens if a SELECT INTO returns multiple rows?

• Oracle raises TOO_MANY_ROWS exception.
• Cursor still closes automatically after the exception.

9. Can we check the life cycle programmatically?

Yes, using SQL cursor attributes immediately after execution:

BEGIN

   DELETE FROM employees WHERE department_id = 999;

 

   IF SQL%NOTFOUND THEN

      DBMS_OUTPUT.PUT_LINE('No rows deleted.');

   ELSE

      DBMS_OUTPUT.PUT_LINE(SQL%ROWCOUNT || ' rows deleted.');

   END IF;

   DBMS_OUTPUT.PUT_LINE('Is cursor open? ' || SQL%ISOPEN);

END;

Output:

No rows deleted.

Is cursor open? FALSE

10. Common mistakes related to implicit cursor life cycle

• Assuming %ISOPEN can be TRUE
• Using %FOUND before statement execution
• Expecting implicit cursor to fetch multiple rows (SELECT INTO fetches only one row)
• Forgetting to handle exceptions (NO_DATA_FOUND, TOO_MANY_ROWS)

11. Best practices

• Always handle exceptions for SELECT INTO
• Use %ROWCOUNT to validate DML operations
• Use implicit cursors for single-row queries or DML operations
• Use explicit cursors for multi-row processing