PL/SQL blocks (Anonymous, Procedures, Functions) Quiz

Explore essential PL/SQL concepts with questions on anonymous blocks, stored procedures, and functions. This quiz assesses your practical understanding of how each block type works, their structure, and differences to strengthen foundational knowledge in PL/SQL programming.

1. Identifying Anonymous Blocks

   Which of the following PL/SQL block examples represents an anonymous block?

   1. CREATE OR REPLACE PROCEDURE show_total IS BEGIN NULL; END;
   2. FUNCTION calc_sum RETURN NUMBER IS BEGIN RETURN 5+5; END;
   3. DECLARE v_total NUMBER; BEGIN v_total := 200; DBMS_OUTPUT.PUT_LINE(v_total); END;
   4. CREATE FUNCTION get_total RETURN NUMBER IS BEGIN RETURN 100; END;

   Explanation: The first option is a standalone block that starts with DECLARE and has no associated name, making it an anonymous block. The second and third options involve the CREATE statement, so they define a function and a procedure respectively, which are both named blocks. The fourth option is a function header without a proper CREATE statement, so it is also incorrect as a standalone anonymous block.

2. Understanding Procedures

   What is a key characteristic of a stored procedure in PL/SQL compared to an anonymous block?

   1. It cannot accept any parameters.
   2. It can be called and reused multiple times by name.
   3. It does not require compilation before execution.
   4. It is always executed automatically with database startup.

   Explanation: A stored procedure is defined and stored in the database, which allows it to be invoked repeatedly by its given name. Anonymous blocks are ad hoc and not stored for reuse. Contrary to option two, procedures do require compilation. Option three is false because procedures can and often do accept parameters. Option four is incorrect since procedures are only executed automatically if explicitly set up to do so, not by default with database startup.

3. Distinguishing Functions from Procedures

   When using a PL/SQL function, what must be true regarding its return value?

   1. It must return a BOOLEAN data type.
   2. It must always return exactly one value.
   3. It does not return any value by definition.
   4. It can only return multiple values as output parameters.

   Explanation: Functions in PL/SQL are required to return exactly one value, and this value is typically used within SQL statements. Option two is a feature of procedures, not functions. Option three is incorrect because only one value can be returned directly by a function, while procedures can have multiple OUT parameters. Option four is wrong because a function can return any supported PL/SQL data type, not just BOOLEAN.

4. Block Structure Components

   Which sequence correctly represents the three main sections of a PL/SQL block?

   1. Open, Run, Close
   2. Begin, Define, End
   3. Start, Process, Error
   4. Declaration, Executable, Exception

   Explanation: A typical PL/SQL block consists of the Declaration section (optional), the Executable section (mandatory), and the Exception handling section (optional). Option two uses terms that do not accurately represent PL/SQL sections. Option three and option four use generic terms unrelated to PL/SQL block structure. Only the first option follows the correct order and names of sections.

5. Valid Use Case for Anonymous Blocks

   In which scenario is an anonymous PL/SQL block the most appropriate choice?

   1. Creating a report that runs on a regular schedule for end users.
   2. Executing a one-time data update script that does not need to be reused.
   3. Defining a reusable business rule that is needed by multiple applications.
   4. Building a complex API interface with external systems.

   Explanation: Anonymous blocks are ideal for quick, ad hoc tasks such as one-time updates or testing because they do not persist in the database. Option two describes a scenario suited for stored procedures or functions, which are reusable. Option three would benefit from a stored procedure or scheduled job. Option four typically requires more formal, reusable code structures than anonymous blocks provide.