PL/SQL Anonymous Blocks – Syntax, Examples & Uses

What is an Anonymous Block in PL/SQL?

In PL/SQL (Procedural Language for SQL), an anonymous block is a basic unit of code that is not named, not stored in the database, and is typically used for quick tasks or testing purposes. As the name implies, it does not have an identifier and is usually written ad hoc in environments like Oracle SQL*Plus or SQL Developer.

Key Characteristics of Anonymous Blocks:

No Name: It doesn’t have an identifier or label.
Temporary: It’s not saved in the database and disappears after execution.
Single-Session Use: Cannot be reused unless copied and re-executed.
Ideal for Testing: Best used for one-time operations, debugging, or simple scripts.
Structure: Starts with DECLARE or BEGIN and ends with END;

Syntax of a PL/SQL Anonymous Block

SET SERVEROUTPUT ON;

DECLARE
   -- Variable declarations (optional)
BEGIN
   -- Executable statements
EXCEPTION
   -- Exception handling (optional)
END;
/

DECLARE: Optional section where variables or constants are defined.
BEGIN: Starts the main code section.
EXCEPTION: Optional section to handle errors.
/: Executes the block in SQL*Plus or tools like Oracle SQL Developer.

Example: Calculate Timestamp for One Hour Ago:

SET SERVEROUTPUT ON;

DECLARE
   v_Date TIMESTAMP;
BEGIN
   SELECT systimestamp - INTERVAL '1' HOUR
   INTO v_Date
   FROM dual;

   DBMS_OUTPUT.PUT_LINE('One hour ago: ' || v_Date);
END;
/

Output:

One hour ago: 12-JUN-25 09.45.22.300000 AM +05:30

When to Use Anonymous Blocks

Use anonymous blocks in situations like:

Testing PL/SQL code snippets
Creating small scripts for admin tasks
Performing quick calculations
Initializing variables during testing
One-time data manipulations

Anonymous Block vs Named Block in PL/SQL – Detailed Comparison

Aspect	Anonymous Block	Named Block (Procedure/Function)
Definition	Block of PL/SQL code with no name, executed once and not stored in the database.	Block of code with a name, stored permanently in the database.
Name	No	Yes
Storage	Not stored in the database	Stored as a database object
Reusability	Cannot be reused unless saved manually	Can be reused by calling its name
Usage Scope	Only within the current session	Globally accessible within schema
Compilation	Compiled at runtime each time	Compiled once and stored
Call from Another Block	Not callable from other blocks	Can be called from other PL/SQL blocks
Parameters Support	Does not accept parameters	Supports IN, OUT, IN OUT parameters
Best Use Case	Testing, scripting, one-time operations	Reusable business logic and APIs
Execution	Executed directly in session	Executed using the procedure/function name
Error Handling	Optional EXCEPTION block	Optional EXCEPTION block

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