52+ PL/SQL Interview Questions Every Developer Should Know in 2025

PL/SQL extends SQL by adding procedural capabilities, enabling developers to manage complex business logic and improve database performance. When optimized, it can reduce network traffic and improve efficiency in data processing.

For database professionals, mastering PL SQL interview questions is of the utmost importance today. This blog will guide you through essential PL SQL interview questions and answers, preparing you to tackle challenges and stand out in the field of database programming.

Basic PL/SQL Interview Questions and Answers for Beginners

Starting your journey in PL/SQL can feel like stepping into a complicated structure of database programming. To help you ace entry-level interviews, it's essential to understand the basics concepts like the structure of PL/SQL, key commands, and how it builds on SQL. 

This section will tackle common beginner PL SQL interview questions that will set you up with the confidence to answer easily. So, let's dive in.

1. What Are The Primary Features That Distinguish PL/SQL From Standard SQL?

PL/SQL adds procedural features to SQL, allowing loops, conditions, and exception handling, making it a more powerful tool for database developers. 

Key features that distinguish PL/SQL from standard SQL include:

• Procedural Capabilities: PL/SQL allows for loops, conditions (IF statements), exception handling, and the ability to define variables, which standard SQL doesn't support.
• Block Structure: PL/SQL code is structured in blocks, which include declarations, executable statements, and exception handlers. This differs from SQL, a declarative language for querying and manipulating data.
• Stored Procedures and Functions: PL/SQL allows developers to define reusable procedures and functions for complex logic, which isn't possible with just SQL.
• Cursors and Exception Handling: PL/SQL provides explicit cursors for fine-grained control over row-by-row processing, which standard SQL handles using set-based operations and analytic functions.

These features allow PL/SQL to handle more complex, procedural logic than standard SQL. 

The course will empower you to solve real-world challenges and open doors to advanced roles in the tech industry.

2. Can You Explain The Concept of A PL/SQL Table and Its Use Cases?

A PL/SQL table is a complex data structure that stores an ordered set of values, similar to an array or collection in other programming languages. PL/SQL tables are also called associative arrays. 

They handle temporary in-memory data, primarily when you must process a set of records without storing them permanently in the database.

Everyday use cases include:

• Storing query results temporarily.
• Manipulating data for reporting.
• Performing complex computations before inserting or updating a table.

PL/SQL tables are useful when performing operations on data without modifying the underlying database tables.

3. What Is The Basic Structure of a PL/SQL Block, and How Is It Organized?

A PL/SQL block is the fundamental unit of PL/SQL code. It consists of three main sections:

1. Declaration Section: This is where you define variables, constants, types, and cursors. It is optional.

DECLARE
    v_count NUMBER;

2. Execution Section: This section contains the main logic, where SQL queries and PL/SQL code are executed. This section is mandatory.

BEGIN
    SELECT COUNT(*) INTO v_count FROM employees;
    DBMS_OUTPUT.PUT_LINE('Number of employees: ' || v_count);
END;

3. Exception Section: This section handles errors (exceptions). It is optional but recommended for robust error handling. 

EXCEPTION
    WHEN NO_DATA_FOUND THEN
        DBMS_OUTPUT.PUT_LINE('No records found');
END;

The structure ensures that PL/SQL can manage data, handle exceptions, and provide output within a single code block.

4. What Is a PL/SQL Cursor, and When Would You Use It?

A PL/SQL cursor is a pointer to a context area that stores information about a SQL query's execution. Cursors are used to fetch multiple rows from a query one at a time.

There are two types:

• Implicit Cursor: Automatically created by Oracle when a SQL query is executed. It's used for single SQL statements like SELECT INTO.
• Explicit Cursor: Defined explicitly by the programmer to handle multi-row queries. It's used when you need to process rows one at a time.

You would use a cursor when you need to process each row of a result set individually, for example, to perform complex calculations or updates.

Also Read: Is SQL Hard to Learn? Breaking Down the Challenges and Solutions

5. How Does the WHERE CURRENT OF Clause Function Within Cursors in PL/SQL?

The WHERE CURRENT OF clause in PL/SQL is used to identify the row being processed by a cursor. It allows for updates or deletes on that specific row within the cursor's context.

This clause can only be used with explicit cursors defined with the FOR UPDATE clause, meaning the cursor retrieves the rows for potential modification.

6. How Can You Assign a Name to an Unnamed Exception Block in PL/SQL?

In PL/SQL, you can assign a name to an unnamed exception block using user-defined exceptions. You can declare and raise a custom exception when a certain condition is met. 

Here’s how you can code it:

DECLARE
    e_custom_exception EXCEPTION;
BEGIN
    -- Some logic
    IF some_condition THEN
        RAISE e_custom_exception;
    END IF;
EXCEPTION
    WHEN e_custom_exception THEN
        DBMS_OUTPUT.PUT_LINE('Custom exception occurred!');
END;

Here, e_custom_exception is a user-defined exception that allows you to handle specific error conditions in your code.

7. What Is a PL/SQL Trigger? Can You Provide Examples of Situations Where Triggers Are Useful?

A PL/SQL trigger automatically runs (or "fires") when a specific event occurs in the database. These events could be changes in a database table, such as an INSERT, UPDATE, or DELETE operation. 

Triggers are primarily used for:

• Enforcing business rules: Automatically applying specific rules when data changes.
• Audit Logging: Automatically tracking changes to data for auditing purposes.
• Preventing invalid operations: Ensuring data integrity by rejecting operations that violate constraints.

Here's an example where triggers are helpful: a trigger that logs changes to a salary column:

CREATE OR REPLACE TRIGGER salary_update_trigger
AFTER UPDATE OF salary ON employees
FOR EACH ROW
BEGIN
    INSERT INTO salary_audit (emp_id, old_salary, new_salary, change_date)
    VALUES (:OLD.emp_id, :OLD.salary, :NEW.salary, SYSDATE);
END;

Explanation: This trigger fires after an UPDATE on the salary field of the employees table. It automatically inserts a record into the salary_audit table with the old and new values of the salary.

To be clear, triggers are not specifically stored procedures. While both contain PL/SQL code, stored procedures must be explicitly called, whereas triggers execute automatically.

8. Under What Circumstances Is the DECLARE Block Required in PL/SQL?

The DECLARE block in PL/SQL is required when you must declare variables, constants, types, and cursors used in the BEGIN (execution) section of the block. 

It is necessary when:

• You want to declare variables to store data that will be used later in the program.
• You need to define user-defined exceptions or types for custom error handling.
• You wish to create cursors for querying and processing data row by row.

For example, in a PL/SQL block, you would typically declare variables in the DECLARE section to store results from queries or process input data.

Also Read: 20 Most Common SQL Query Interview Questions & Answers [For Freshers & Experienced]

9. What Are the Proper Conventions for Writing Comments in PL/SQL Code?

Writing explicit comments in PL/SQL is crucial for improving code readability and maintainability. Proper commenting conventions should be followed to ensure anyone reading the code can easily understand its logic.

1. Single-Line Comments: These comments begin with two dashes (--) and are used for brief explanations.
2. Multi-Line Comments: These comments are enclosed between /* and */ and are helpful for longer explanations or for commenting out large blocks of code. 
3. Inline Comments: Comments can also be placed at the end of a line of code to explain the logic in that statement.

Good comments are critical in making your code understandable and maintainable, especially when working on large systems or collaborating with teams.

10. How Does the WHEN Condition in a Trigger Impact Its Execution?

The WHEN condition in a PL/SQL trigger controls whether the trigger will fire or not. It’s a condition that must be evaluated to TRUE for the trigger to execute. 

This gives you greater control over when the trigger should run, allowing you to implement more refined logic based on manipulated data.

For example, you might have an AFTER INSERT trigger that only fires if a particular condition is met—such as when the new employee's salary exceeds a threshold.

Here's how:

CREATE OR REPLACE TRIGGER salary_check_trigger
AFTER INSERT ON employees
FOR EACH ROW
WHEN (NEW.salary > 10000)
BEGIN
    DBMS_OUTPUT.PUT_LINE('High salary inserted: ' || :NEW.emp_name);
END;

This trigger will only fire if the salary of the newly inserted employee exceeds 10,000. The WHEN condition checks the NEW.salary value before the trigger executes.

11. How Does PL/SQL Differ From SQL in Terms of Functionality and Use Cases?

PL/SQL and SQL are both integral parts of Oracle databases, but they serve different purposes:

• SQL (Structured Query Language): SQL is a declarative language used for querying and managing data in a database. 

  It is designed to define, manipulate, and retrieve data through operations like SELECT, INSERT, UPDATE, and DELETE. SQL handles data manipulation and is great for set-based operations.

  Use cases: Querying data, creating tables, updating records, etc.

• PL/SQL (Procedural Language/SQL): PL/SQL extends SQL by adding procedural programming capabilities. It allows for using variables, loops, conditions, exceptions, and more. 

  PL/SQL is used to write complex logic that involves multiple SQL statements, and it is beneficial for business logic and data processing.

  Use cases: Automating repetitive tasks, handling complex business logic, creating stored procedures and triggers.

  PL/SQL is used when you combine SQL operations with procedural logic to handle complex tasks that cannot be accomplished with SQL alone.

12. What Is the Purpose of the SYSDATE and USER Keywords in PL/SQL?

SYSDATE is a built-in function in PL/SQL that returns the current date and time of the system where the database is running. It's commonly used for timestamping records or calculating time intervals.

Use case: Often used for logging events, recording the date of transactions, or calculating durations between two dates.

Meanwhile, the USER keyword returns the current database username. It helps identify the user running a particular PL/SQL block, especially in multi-user environments or when managing security.

Use case: Typically used in auditing or when you need to track which database user is executing certain operations.

13. What Is The Difference Between An Implicit Cursor And An Explicit Cursor In PL/SQL?

PL/SQL uses cursors to handle the results of SQL queries. While both implicit and explicit cursors serve the same purpose of handling multiple rows, they differ in how they are defined and managed:

1. Implicit Cursor: Oracle automatically creates implicit cursors when you execute a single SQL statement that returns a result. It is managed by Oracle internally and does not require you to declare or open it explicitly.
2. Explicit Cursor: You explicitly define an explicit cursor when you want more control over the query and its results. It's useful when working with multiple rows that need to be processed individually (e.g., looping through the result set).

14. Why Are %TYPE And %ROWTYPE Data Types Essential In PL/SQL Programming?

Both %TYPE and %ROWTYPE are consequential data types in PL/SQL that help you write more flexible and maintainable code.

• %TYPE: This attribute allows you to declare a variable with the same data type as a column or another variable. 

  This ensures that the variable always matches the column's data type or variable, even if the type changes in the database. It promotes consistency and reduces errors when the database schema is modified.

• %ROWTYPE: This attribute allows you to declare a variable that holds an entire row of data from a table. 

  It’s particularly useful when you want to handle records that consist of multiple columns, as it ensures that the variable structure matches the table structure.

Also Read: A Comprehensive Guide to Understanding the Different Types of Data

15. What Are The Key Differences Between ROLLBACK And ROLLBACK TO Statements In PL/SQL?

In PL/SQL, both ROLLBACK and ROLLBACK TO are used to undo changes made during the current transaction. 

However, they have different scopes and use cases:

1. ROLLBACK: This statement undoes all changes made during the current transaction unless a savepoint is specified, in which case it can roll back only part of the transaction.

After issuing a ROLLBACK, all changes are discarded, and the database returns to its previous consistent state.

2. ROLLBACK TO: This statement undoes changes up to a specific savepoint, allowing you to roll back only part of a transaction. 

A savepoint is a marker set during a transaction that allows you to return to a specific point rather than rolling back the entire transaction.

16. What Is The Role of SYS.ALL_DEPENDENCIES In PL/SQL?

The SYS.ALL_DEPENDENCIES view in PL/SQL provides information about the dependencies between database objects. It helps you identify which objects depend on others, allowing you to manage and troubleshoot dependencies effectively.

While the USER_DEPENDENCIES should be used when checking dependencies for objects owned by the current user.

• Key Purpose: It is commonly used to identify dependent objects that might be affected by changes (e.g., dropping or altering a table, view, or package).
• Use Case: Before dropping or modifying an object, you can query ALL_DEPENDENCIES to check for any dependent objects that might break due to your changes.

17. What Are The Virtual Tables Created During The Execution of a Database Trigger in PL/SQL?

In PL/SQL, when a trigger is fired, Oracle automatically creates two unique virtual tables to hold the old and new values of the rows manipulated by the trigger. These virtual tables are:

• :NEW: This pseudo-record holds the new values for the row after an INSERT or UPDATE operation. It is used to access the values that are being inserted or updated.
• :OLD: This pseudo-record holds the old values for the row before an UPDATE or DELETE operation. It is used to access the original values before they are modified or deleted.

These virtual tables are handy in AFTER INSERT, AFTER UPDATE, and AFTER DELETE triggers for auditing, logging changes, or implementing complex business rules.

18. How Does the Declaration of Cursors Differ in Procedures Compared to Package Specifications?

The declaration of cursors in PL/SQL procedures and package specifications differs mainly in their scope and usage.

• In Procedures: Cursors are declared locally within the procedure. They are only available for use inside that specific procedure or block.
• In Package Specifications: Cursors declared in a package specification are accessible to all procedures and functions within that package, which makes them reusable across multiple subprograms in the package.

19. How Do COMMIT, ROLLBACK, And SAVEPOINT Statements Function in PL/SQL?

In PL/SQL, the COMMIT, ROLLBACK, and SAVEPOINT statements are used to manage the database's transaction flow and data consistency.

1. COMMIT: This statement is used to permanently save all the changes made during the current transaction to the database. Once a COMMIT isissued, the changes are visible to all other users, and the transaction is concluded.
2. ROLLBACK: This statement undoes all changes made in the current transaction, reverting the database to its previous state before the transaction started.
3. SAVEPOINT: This statement sets a point within a transaction you can roll back to without undoing the entire transaction. You can set multiple savepoints within a transaction and roll back to any of them as needed.

20. What Strategies Can Be Used to Debug PL/SQL Code Effectively?

Debugging PL/SQL code can sometimes be challenging due to the complexity of stored procedures and triggers. However, several strategies can help identify and fix errors efficiently:

• DBMS_OUTPUT.PUT_LINE: Use this built-in procedure to print out variable values and execution flow. It's a simple and effective debugging tool for checking variable contents and verifying logic.
• Exception Handling: Use exception handling to capture and log errors. This can help identify issues in your code and provide meaningful error messages.

• SQL*Plus Debugging: In SQL*Plus or SQLcl, you can enable debugging with the 

  SET SERVEROUTPUT ON 

  command to view the output of the

  DBMS_OUTPUT.PUT_LINE 

  statements.

• Use of IDEs: Many Integrated Development Environments (IDEs), such as Oracle SQL Developer or TOAD, offer debugging tools to set breakpoints, step through code, and inspect variables in real time.
• Unit Testing: Writing unit tests for your PL/SQL code ensures that individual components work as expected. This helps isolate bugs early in the development process.

21. What Is The Difference Between A Mutating Table and A Constraining Table in PL/SQL?

In PL/SQL, mutating tables and constraining tables are terms related to triggers. They define the type of operations performed on a table during a trigger's execution.

1. Mutating Table 

A mutating table occurs when a trigger attempts to modify or query the same table that fired the trigger. Oracle does not allow certain actions on mutating tables because it can lead to inconsistent results or infinite loops in triggers.

Suppose you have a BEFORE UPDATE trigger on the employees table, and you attempt to query the employees table within the trigger. This would result in a mutating table error, as the trigger is fired by modifying the same table.

Solution: To avoid this, you can use compound triggers or store affected row IDs in a collection and process them in an AFTER statement-level trigger.

2. Constraining Table 

A constraining table is a table involved in a referential integrity constraint, such as foreign key constraints. These tables can be updated within triggers because the database usually maintains its referential integrity, and Oracle allows these operations.

Now that you are familiar with the PL/SQL concepts, it's time to dive deeper into more complex topics. 

Also Read: SQL vs PL/SQL: Difference Between SQL & PL/SQL

Let's move to intermediate-level PL SQL interview questions that will challenge your understanding of advanced features.

PL/SQL Interview Questions to Sharpen Your Skills at an Intermediate Level

To proceed further, you must tackle the more intricate parts of PL/SQL, like creating efficient stored procedures, handling errors gracefully, and optimizing performance. These skills are valuable when you're working on real-world projects where every line of code counts. 

With these intermediate concepts, you'll enhance your PL/SQL proficiency and gain the confidence to solve complex problems. So, let’s explore.

1. Can You Outline The Various Data Types Available In PL/SQL And Their Use Cases?

PL/SQL offers a variety of data types, allowing you to define variables that can store different kinds of data. The primary categories include:

• Scalar Types: These include:
  • NUMBER: For numeric data (e.g., INTEGER, DECIMAL).
  • VARCHAR2: For variable-length strings (e.g., CHAR or TEXT).
  • DATE: For storing date and time values.
  • BOOLEAN: For true/false values.
• Composite Types:
  • RECORD: A collection of related data types, grouped together.
  • TABLE: A collection of elements of the same type, useful for array-like structures.
• LOB Types (Large Object):
  • BLOB: For binary data like images.
  • CLOB: For large character objects, useful for storing large amounts of text.

These data types are crucial for defining variables, parameters, and columns in PL/SQL and help ensure the right format and behavior for your data operations.

Also Read: Data Types in C and C++ Explained for Beginners

2. What Are The Different Types Of Exceptions In PL/SQL? Could You Provide Examples?

In PL/SQL, exceptions are errors or other events that disrupt the normal flow of execution. There are two main types:

1. Predefined Exceptions: These are built-in exceptions that PL/SQL automatically raises. Examples include:

• NO_DATA_FOUND: Raised when a SELECT INTO query returns no rows.
• TOO_MANY_ROWS: Raised when a SELECT INTO query returns more than one row.
• ZERO_DIVIDE: Raised when attempting to divide by zero.

For Example:

BEGIN
    SELECT column_name INTO var FROM table WHERE condition;
EXCEPTION
    WHEN NO_DATA_FOUND THEN
        DBMS_OUTPUT.PUT_LINE('No data found');
END;

2. User-Defined Exceptions: These allow you to define custom errors for specific situations. You can raise these exceptions manually using the RAISE keyword.

For Example:

DECLARE
    my_exception EXCEPTION;
BEGIN
    RAISE my_exception;
EXCEPTION
    WHEN my_exception THEN
        DBMS_OUTPUT.PUT_LINE('Custom exception occurred');
END;

Handling exceptions effectively helps ensure smooth error management in PL/SQL programs, allowing for specific actions based on different error types.

3. Are There Any SQL Commands That PL/SQL Does Not Support? If So, Which Ones?

PL/SQL, while offering powerful procedural capabilities, does not support all SQL commands directly. Some key SQL commands not supported by PL/SQL include:

1. DDL Commands (Data Definition Language)

These include CREATE, ALTER, and DROP (for tables, views, and indexes). These commands cannot be executed directly inside a PL/SQL block. To run these commands, you would need to use dynamic SQL with the EXECUTE IMMEDIATE statement.

2. TRUNCATE Command 

While DELETE is supported in PL/SQL, TRUNCATE cannot be used directly within a PL/SQL block. It's a DDL command and behaves differently (e.g., it can't be rolled back).

These restrictions help maintain the integrity and stability of the PL/SQL environment while focusing on data manipulation and procedural logic.

4. Can You Name Some Common PL/SQL Exceptions And Explain When They Might Occur?

Common PL/SQL exceptions include:

• NO_DATA_FOUND: Raised when a SELECT INTO query returns no rows. It often occurs when attempting to fetch a record that does not exist.
• TOO_MANY_ROWS: Raised when a query returns more than one row when only one is expected. This can occur in cases where the data set isn't unique.
• ZERO_DIVIDE: Raised when trying to divide by zero. It happens in mathematical operations when the divisor is zero.
• INVALID_CURSOR: Raised when an operation is attempted on an invalid cursor, like trying to fetch from a closed cursor.

Handling these exceptions gracefully ensures that your code can react to errors, providing meaningful feedback or recovery strategies.

Also Read: Top 32 Exception Handling Interview Questions and Answers [For Freshers & Experienced]

5. What Exactly Is A PL/SQL Package? How Does It Help In Organizing Code?

A PL/SQL package is a collection of related procedures, functions, variables, and other PL/SQL elements grouped together. A package consists of two parts:

1. Package Specification: Defines the interface to the package, such as public procedures and functions. It declares the package's accessible elements.
2. Package Body: Contains implementing the procedures and functions declared in the package specification.

Packages help organize code, making it modular and reusable. They also improve performance by reducing the need to recompile the code and provide a more structured programming approach.

6. Write A PL/SQL Program That Checks If A Given String Is A Palindrome.

A palindrome is a word or phrase that reads the same forward and backward. Here's a PL/SQL program that checks if a string is a palindrome:

DECLARE
    original_string VARCHAR2(100) := 'madam';
    reversed_string VARCHAR2(100);
BEGIN
    reversed_string := REVERSE(original_string); -- Reversing the string

    IF original_string = reversed_string THEN
        DBMS_OUTPUT.PUT_LINE('The string is a palindrome.');
    ELSE
        DBMS_OUTPUT.PUT_LINE('The string is not a palindrome.');
    END IF;
END;

Output:

The string is a palindrome.

Code Explanation:

• REVERSE(original_string) reverses the string.
• If the reversed string matches the original, it outputs "The string is a palindrome."

7. What Command Would You Use To Remove A Package In PL/SQL, And What Is The Syntax?

To remove a PL/SQL package, use the DROP PACKAGE command. The syntax is:

DROP PACKAGE my_package;

This removes both the package specification and package body from the database.

Output:

Package dropped.

8. How Do You Execute A Stored Procedure In PL/SQL, And What Are The Requirements?

To execute a stored procedure in PL/SQL, you can either use the EXECUTE statement or call it within an anonymous PL/SQL block.

Example using EXECUTE:

EXECUTE my_procedure;

Alternatively:

BEGIN
    my_procedure;
END;

Output:

Procedure executed successfully.

The key requirements for this include:

• The procedure must be compiled and valid.
• It must be accessible with the necessary privileges.
• If parameters are involved, they need to be passed correctly.

9. Can You Explain The Difference Between IN, OUT, And IN OUT Parameters In PL/SQL?

In PL/SQL, parameters allow values to be passed to and from procedures and functions. Here's how they differ:

• IN: The parameter is used to pass values into the procedure or function. It's read-only within the subprogram. 

  Example: PROCEDURE my_procedure(x IN NUMBER);

• OUT: The parameter is used to return a value from the procedure or function. It's write-only and does not have a value when passed in.

  Example: PROCEDURE my_procedure(y OUT NUMBER);

• IN OUT: The parameter is used to pass values into the procedure or function and also to return a value. It is both read and write.

  Example: PROCEDURE my_procedure(z IN OUT NUMBER);

10. How Do %ROWTYPE And %TYPE Differ, And When Would You Use Each In PL/SQL?

%ROWTYPE attribute defines a variable that can hold an entire row of a table or view. It is used when you want to store a complete record from a table.

Here’s when it is used:

DECLARE
    employee_record employees%ROWTYPE;
BEGIN
    SELECT * INTO employee_record FROM employees WHERE emp_id = 101;
END;

Output:

Record fetched for emp_id 101.

Meanwhile, the %TYPE attribute defines a variable based on the data type of a column in a table or a previously declared variable. It ensures that the variable has the same type as the column.

Here’s when it is used:

DECLARE
    salary employees.salary%TYPE;
BEGIN
    SELECT salary INTO salary FROM employees WHERE emp_id = 101;
END;

Output:

Salary fetched for emp_id 101.

11. What Are SQLERRM And SQLCODE, And How Do They Assist In Error Handling In PL/SQL?

SQLCODE returns the error number of the most recent exception encountered. It helps identify specific errors by their numerical code.

Here’s how it assists in error handling:

BEGIN
    -- Some code that causes an error
EXCEPTION
    WHEN OTHERS THEN
        DBMS_OUTPUT.PUT_LINE('Error Code: ' || SQLCODE);
END;

Output:

Error Code: -6502

However, SQLERRM returns the error message associated with the most recent exception. It provides a description of the error.

Here’s how:

BEGIN
    -- Some code that causes an error
EXCEPTION
    WHEN OTHERS THEN
        DBMS_OUTPUT.PUT_LINE('Error Message: ' || SQLERRM);
END;

Output:

Error Message: ORA-06502: PL/SQL: numeric or value error

12. What Are PL/SQL Records, And Can You Explain The Different Types Of Records Used?

PL/SQL records are composite data types that allow you to group multiple related fields of different data types into a single variable. These are especially useful when working with structured data or representing table rows.

There are two types of records:

1. Explicit Records: The user defines these and allows you to specify the exact structure. You define a record by creating a user-defined type that groups various fields of different data types. Example:

2. %ROWTYPE Records: These records are automatically created based on a table or view's structure. They allow you to directly store a row from a table or a query result.

Both types of records help handle complex data structures in a streamlined way, improving code readability and maintainability.

13. What Are The BTITLE and TTITLE Commands Used For PL/SQL?

In PL/SQL, the BTITLE and TTITLE commands are used to format and print reports, making it easier to display well-organized output, especially for reports generated in SQL*Plus or other Oracle environments. 

These commands control the titles and headers for your reports, adding clarity and structure.

1. TTITLE: Used to define the top title of a report. You can use it to set a title that will appear at the top of the report page.
2. BTITLE: This command sets the bottom title of the report, allowing you to place additional information like page numbers or timestamps at the bottom of the report.

Using TTITLE and BTITLE allows you to enhance the readability and professionalism of your report outputs. For instance, you could display a report title at the top and a page footer at the bottom, making the output more organized.

Also Read: Free SQL Certification Course Online [2025]

14. What Are The Valid Formats For DateTime Values In PL/SQL, Especially For Seconds?

In PL/SQL, handling date and time values is crucial for accurate data processing, mainly when working with time-sensitive applications. The DATE data type in PL/SQL stores both the date and time, but it has specific formats for representing these values.

• Default Format: The default format for DATE includes both date and time like below:

DD-MON-YY HH24:MI:SS

Example: 15-FEB-25 14:30:00

• Valid Formats:
  • YYYY: Four-digit year.
  • MM: Two-digit month (01-12).
  • DD: Day of the month (01-31).
  • HH24: Hour in 24-hour format (00-23).
  • MI: Minutes (00-59).
  • SS: Seconds (00-59).

For instance, if you want to insert a timestamp with seconds, you would format it like this:

TO_DATE('2025-02-15 14:30:45', 'YYYY-MM-DD HH24:MI:SS')

This ensures that PL/SQL handles both the date and the exact time down to the second, which is useful for applications like logging events or scheduling tasks.

15. How Do PL/SQL Delimiters Work, And What Role Do They Play In Code Execution?

PL/SQL delimiters are critical in distinguishing different code sections, particularly when you're writing anonymous blocks or scripts that include multiple statements. Delimiters help to separate logic and control the flow of execution. 

The most commonly used delimiters are semicolons (;) and slashes (/).

1. Semicolon (;): This marks the end of a PL/SQL statement. A semicolon terminates every individual statement within a PL/SQL block.

2. Slash (/): This executes an anonymous PL/SQL block in SQL*Plus after the block has been entirely written. It is typically used at the end of a PL/SQL anonymous block to execute the entire block.

   The slash tells SQLPlus to execute the block. Without this delimiter, the code would not be executed immediately in SQLPlus.

These delimiters help structure and execute PL/SQL code efficiently, ensuring that the Oracle database properly recognizes and interprets the code.

Also Read: Most Asked Oracle Interview Questions and Answers – For Freshers and Experienced

16. How Is The UTL_FILE Package Used In PL/SQL, And What Functionality Does It Provide?

The UTL_FILE package is a built-in utility in PL/SQL that provides functionality for reading from and writing to operating system files. This package is essential for file handling in PL/SQL, allowing developers to manipulate files on the server's file system.

File Operations: With UTL_FILE, you can:

• Open a file for reading or writing.
• Read and write data line by line.
• Close a file after operations are complete.

The UTL_FILE package generates reports, logs events, or exports data outside the database to external files.

17. How Does Indexing Work In PL/SQL, And Why Is It Important?

Indexing in PL/SQL is a mechanism that enhances the speed of data retrieval operations on large datasets. An index is a data structure that allows for fast lookups on a table's columns, reducing the time required to fetch data.

How Indexing Works: 

An index is created on one or more table columns, providing a way to quickly locate rows in a table without scanning it thoroughly. It works like an index in a book, allowing you to jump directly to the page you're looking for.

Why It's Important:

Indexes dramatically speed up the search for rows based on indexed columns. Without indexes, queries like 

SELECT * FROM employees WHERE emp_id = 101; 

would have to scan every row in the table.

However, there are trade-offs. Indexes can slow down INSERT, UPDATE, and DELETE operations since the index needs to be updated every time the underlying data changes. Thus, indexes should be used wisely.

18. What Does The Error ORA-03113 Indicate, And How Should It Be Handled?

The error ORA-03113: end-of-file on communication channel is a standard Oracle error indicating a lost connection between the client and the server. 

This could happen for a variety of reasons, such as:

• A network issue is causing the connection to drop.
• The database server crashing or being restarted.
• Timeout due to long-running queries or idle connections.

Handling the Error:

• Check Network Connectivity: Ensure no network outage or firewall is blocking the connection.
• Review Database Logs: Look at the Oracle alert logs to identify if the database crashed or experienced any internal issues.
• Retry Connection: You may need to reconnect to the database or restart the session to resolve the issue.

By addressing the root cause, you can mitigate the occurrence of this error.

19. How Would You Explain A SQL JOIN, And What Are The Different Types Available In PL/SQL?

In SQL, a JOIN operation combines rows from two or more tables based on a related column between them. The most common types of joins are:

1. INNER JOIN: Returns rows that have matching values in both tables.

SELECT employees.emp_id, employees.emp_name, departments.dept_name
FROM employees
INNER JOIN departments ON employees.dept_id = departments.dept_id;

2. LEFT JOIN (or LEFT OUTER JOIN): Returns all rows from the left table and matches rows from the right table. If there is no match, NULL is returned for columns from the right table.

SELECT employees.emp_id, employees.emp_name, departments.dept_name
FROM employees
LEFT JOIN departments ON employees.dept_id = departments.dept_id;

3. RIGHT JOIN (or RIGHT OUTER JOIN): Similar to the left join, but returns all rows from the right table.

4. FULL JOIN: Returns all rows when a match occurs in one of the tables.

Joins are essential for combining related data from multiple tables, and understanding the various types helps optimize data retrieval.

20. How Can Multiple Tables Be Created And Managed Within A PL/SQL Block?

In PL/SQL, you can create multiple tables within a PL/SQL block using dynamic SQL or executing CREATE TABLE commands. 

While PL/SQL doesn't directly support creating multiple tables within a block without dynamic SQL, it can handle multiple operations efficiently when using EXECUTE IMMEDIATE to run CREATE commands.

Here’s an example where multiple tables are created using dynamic SQL in PL/SQL:

BEGIN
    EXECUTE IMMEDIATE 'CREATE TABLE employees (emp_id NUMBER, emp_name VARCHAR2(100))';
    EXECUTE IMMEDIATE 'CREATE TABLE departments (dept_id NUMBER, dept_name VARCHAR2(100))';
    DBMS_OUTPUT.PUT_LINE('Tables created successfully.');
END;

Output:

Tables created successfully.

Code Explanation:

• EXECUTE IMMEDIATE: This command allows you to execute the CREATE TABLE statements within the PL/SQL block.
• Each table creation command is issued separately but executed within the same PL/SQL block.

This method is proper when creating and managing multiple tables dynamically within a PL/SQL environment, especially in scenarios like data migrations or automated setup scripts.

There you go! Now that you have covered key intermediate PL SQL interview questions and answers,  it's time to take your skills to an expert level. 

Also Read: PL SQL Developer Salary in India: For Freshers & Experienced [2024]

Advanced PL/SQL Interview Questions for Skilled Developers

To become a seasoned developer, from effective debugging and tracing techniques to working with nested tables and fine-tuning performance, you must learn strategies to optimize your database processes and tackle real-world challenges. 

These advanced skills will help you build more efficient, scalable, and robust PL/SQL applications, enabling you to enhance database performance in high-demand environments.

So, let’s explore some expert-level PL SQL interview questions and answers.

1. Could You Explain How RAISE_APPLICATION_ERROR Is Used in PL/SQL and Why It's Important?

The RAISE_APPLICATION_ERROR procedure in PL/SQL is used to raise user-defined exceptions with custom error messages. This is particularly important when controlling error handling and returning meaningful error messages to the calling program or application. 

Unlike built-in exceptions, it allows you to define custom error codes (ranging from -20000 to -20999) and corresponding messages.

Why it’s important:

• It provides more meaningful and specific error messages than the default Oracle errors.
• It allows for better debugging and user notification.
• It enables you to raise errors in stored procedures or functions when certain business rules are violated.

2. What Is the Purpose of PRAGMA_EXCEPTION_INIT in PL/SQL, and When Would You Use It?

The PRAGMA_EXCEPTION_INIT directive is used to associate a user-defined exception with a specific Oracle error number. This allows you to handle Oracle error codes more meaningfully and structured within PL/SQL.

Key Purpose:

• It enables you to define custom exceptions that are linked to specific Oracle error numbers.
• Helps in handling Oracle error codes more effectively, making your code more readable and maintainable.

It is typically used when you want to define specific actions for particular Oracle errors in your PL/SQL block, and the standard exception handlers do not handle the error.

3. How Can You Determine if an UPDATE Statement Was Successfully Executed in PL/SQL?

In PL/SQL, you can use the SQL%ROWCOUNT attribute to determine how many rows were affected by an UPDATE statement. This is particularly useful for confirming if the statement successfully updated any rows.

Here’s an example to execute it:

BEGIN
    UPDATE employees SET salary = salary + 500 WHERE emp_id = 101;
    IF SQL%ROWCOUNT > 0 THEN
        DBMS_OUTPUT.PUT_LINE('Rows updated successfully.');
    ELSE
        DBMS_OUTPUT.PUT_LINE('No rows updated.');
    END IF;
END;

Code Explanation:

• SQL%ROWCOUNT returns the number of rows affected by the most recent SQL statement.
• If the UPDATE modifies one or more rows, the message "Rows updated successfully" is displayed; otherwise, it indicates no rows were updated.

Using SQL%ROWCOUNT is essential for verifying the success of DML operations like UPDATE.

4. What Does the || Operator Do in PL/SQL, and How Is It Useful?

The || operator in PL/SQL is used for string concatenation. It combines two or more strings into a single string. This operator is widely used when creating a larger string from smaller components, such as combining text and variables or database columns.

Here’s how it is used:

DECLARE
    v_first_name VARCHAR2(50) := 'John';
    v_last_name VARCHAR2(50) := 'Doe';
    v_full_name VARCHAR2(100);
BEGIN
    v_full_name := v_first_name || ' ' || v_last_name;
    DBMS_OUTPUT.PUT_LINE('Full Name: ' || v_full_name);
END;

Output:

Full Name: John Doe

Here, the || operator concatenates v_first_name, a space (' '), and v_last_name to form the full name.

This operator is invaluable when you need to format strings or generate dynamic text in PL/SQL.

Also Read: Understanding the Types of SQL Operators: Practical Examples and Best Practices

5. Is It Possible to Use Definition Commands Like CREATE in PL/SQL? Why or Why Not?

In PL/SQL, DDL commands are generally not allowed inside a PL/SQL block because they are part of the Data Definition Language, which operates outside the scope of PL/SQL’s procedural execution model. 

However, you can execute these commands dynamically using dynamic SQL i.e. EXECUTE IMMEDIATE inside PL/SQL.

Why not directly in PL/SQL?

DDL commands in PL/SQL are transaction-control statements and cause implicit commits, which makes them incompatible with the transactional nature of PL/SQL.

Solution: Use EXECUTE IMMEDIATE to execute DDL commands dynamically.

6. What Is a View in PL/SQL, and How Do You Use It in Database Queries?

A view in PL/SQL is a virtual table that provides a way to simplify complex queries. It is essentially a stored query that can be treated as a table. Views are practical for presenting data in a simplified or summarized manner without modifying the actual tables.

Use Case: You use views to encapsulate complex logic and simplify querying. Views can hide the complexity of joins, aggregates, and data transformations.

Here’s how you can use it in the database queries:

CREATE VIEW employee_summary AS
SELECT department_id, COUNT(*) AS total_employees, AVG(salary) AS avg_salary
FROM employees
GROUP BY department_id;

This view simplifies querying the total number of employees and their average salary by department. Instead of writing the SELECT query each time, you can simply query the employee_summary view.

Querying the View:

SELECT * FROM employee_summary;

Output: Displays summarized employee data by department.

Also Read: Types of Views in SQL

7. What Are the Fundamental Components of a PL/SQL Trigger, and How Do They Interact?

A PL/SQL trigger is a stored procedure that automatically executes in response to specific events like INSERT, UPDATE, or DELETE operations on a table. 

The fundamental components of a PL/SQL trigger are:

• Trigger Name: The identifier for the trigger.
• Trigger Timing: Specifies when the trigger should fire — either BEFORE or AFTER the DML operation.
• Trigger Event: The type of DML operation that fires the trigger (e.g., INSERT, UPDATE, or DELETE).
• Trigger Body: Contains the PL/SQL code executed when the trigger is fired.
• Trigger Level: Specifies whether the trigger should fire once for each row (row-level trigger) or once for the entire statement (statement-level trigger).

Here's how they interact:

CREATE OR REPLACE TRIGGER before_insert_employee
BEFORE INSERT ON employees
FOR EACH ROW
BEGIN
    :NEW.creation_date := SYSDATE;
END;

This trigger automatically sets the creation_date column when a new row is inserted.

8. What Are the Various Methods Available for Tracing PL/SQL Code Execution?

Tracing PL/SQL code execution helps diagnose performance issues, understand code flow, and debug errors. There are several methods to trace PL/SQL code:

1. DBMS_OUTPUT: This package displays debug information during code execution using DBMS_OUTPUT.PUT_LINE.
2. Oracle Trace: Use SQL Trace (ALTER SESSION SET SQL_TRACE = TRUE;) to capture detailed information on PL/SQL execution and performance.
3. TKPROF: This tool processes the output of SQL Trace to analyze performance metrics like execution time and resource usage.
4. PL/SQL Profiler: Oracle provides an integrated profiler for identifying PL/SQL code performance bottlenecks.

Each method serves a different purpose: DBMS_OUTPUT for simple debugging, Oracle Trace and TKPROF for performance monitoring, and the Profiler for detailed insights.

9. How Can You Create and Work with Nested Tables in PL/SQL? What Are Their Advantages?

A nested table is a collection type in PL/SQL that allows you to store an unordered set of elements, similar to an array. Unlike associative arrays, nested tables are stored in the database and can be queried like a standard table.

Creating a Nested Table:

• Define a nested table type using the CREATE TYPE statement.
• Use the nested table in a PL/SQL block or stored procedure.

Key Advantages:

• Flexibility in storing collections of data.
• It can be queried directly using SQL for persistence and retrieval.
• Supports operations like INSERT, UPDATE, and DELETE.

10. How Can You Implement Dynamic SQL in PL/SQL? What Are the Benefits of Using It?

Dynamic SQL in PL/SQL allows you to construct and execute SQL statements dynamically at runtime. This is useful when building SQL queries or DDL statements based on user input or application logic.

To implement it, you use the EXECUTE IMMEDIATE statement to execute dynamic SQL. Here’s how:

DECLARE
    v_sql VARCHAR2(100);
BEGIN
    v_sql := 'UPDATE employees SET salary = salary + 1000 WHERE emp_id = 101';
    EXECUTE IMMEDIATE v_sql;
END;

Explanation:

• EXECUTE IMMEDIATE dynamically executes the SQL query stored in v_sql.
• This allows flexible, run-time SQL construction.

The key benefits of using dynamic SQL in PL/SQL include:

• Allows handling dynamic queries with variable table names, columns, or conditions.
• Useful for cases where the SQL structure needs to be determined based on runtime conditions (e.g., dynamic reports).

11. What Is the Concept of a "Pipeline Function" in PL/SQL, and How Can It Be Used to Return a Result Set?

A pipeline function in PL/SQL is a special function that returns a result set to the calling query. It can return rows incrementally, similar to a table or view, and is helpful for operations requiring a result set without materializing the data in memory all at once.

Pipeline functions are often used for streaming data or large datasets, enabling more efficient handling without loading everything into memory.

For Example:

CREATE OR REPLACE FUNCTION get_employee_salary (p_department_id IN NUMBER)
  RETURN employee_salary_tab PIPELINED IS
BEGIN
  FOR rec IN (SELECT emp_name, salary FROM employees WHERE dept_id = p_department_id) LOOP
    PIPE ROW (rec.emp_name, rec.salary);
  END LOOP;
  RETURN;
END;

Explanation:

• The PIPELINED keyword defines a pipeline function.
• PIPE ROW sends individual rows to the result set, which can be queried like a table.

Querying the Pipeline Function:

SELECT * FROM TABLE(get_employee_salary(10));

Output:

The query returns the emp_name and salary from the pipeline function for department 10.

12. How Do You Handle Large Objects (LOBs) in PL/SQL, and What Techniques Can Be Used for Efficient Handling?

Handling Large Objects (LOBs) in PL/SQL requires special consideration, as LOBs (like BLOB, CLOB, NCLOB) can store very large data (e.g., images, documents). PL/SQL provides the DBMS_LOB package for efficient handling.

Techniques:

• Using DBMS_LOB: Functions such as CREATETEMPORARY, WRITE, and SUBSTR allow manipulation of LOBs.
• Efficient Memory Handling: For large LOBs, use chunking techniques to read or write data in parts rather than loading the entire object into memory.

Best Practices:

• Buffering: Use buffered LOB operations for efficient data handling.
• Chunking: Read and write LOBs in smaller chunks to optimize memory usage.

13. What Is the Difference Between a Function and a Procedure in PL/SQL, and When Should You Use Each?

Both functions and procedures in PL/SQL are subprograms that can encapsulate logic, but they differ in their usage and purpose.

1. Function: A function performs a specific task and always returns a single value. It can be used in SQL statements (e.g., SELECT) or as part of expressions.

Use Case: Functions are best used when you need to return a value, perform a calculation, or retrieve a result.

2. Procedure: A procedure performs a series of actions but does not return a value. It is typically used to execute business logic, update records, or perform tasks that do not require returning a value.

Use Case: Procedures are ideal for actions like data manipulation or database updates where no return value is needed.

Key Differences are:

• The Function returns a value, while the Procedure does not.
• Functions can be used in SQL queries, whereas procedures are executed using a CALL or EXECUTE statement.

14. Can You Explain the Use of DBMS_SCHEDULER in PL/SQL and How It Is Applied for Automating Tasks?

The DBMS_SCHEDULER package in PL/SQL schedules and automates jobs, tasks, or scripts at specified times or intervals. It is beneficial for scheduling routine database maintenance tasks, reporting, and running batch jobs.

Key Components:

• Job: A task that is executed on the scheduled time.
• Schedule: Defines when and how often the job will run (e.g., daily, weekly).
• Program: Defines the logic or command that the job will execute.

Here’s how it can be applied for automating tasks:

BEGIN
    DBMS_SCHEDULER.create_job(
        job_name        => 'daily_salary_update',
        job_type        => 'PLSQL_BLOCK',
        job_action      => 'BEGIN UPDATE employees SET salary = salary + 100 WHERE department_id = 10; END;',
        start_date      => SYSTIMESTAMP,
        repeat_interval => 'FREQ=DAILY; BYHOUR=0; BYMINUTE=0; BYSECOND=0',
        enabled         => TRUE
    );
END;

Code Explanation:

• This job runs the UPDATE statement to increase employees' salary in department 10 daily at midnight.
• The create_job procedure from DBMS_SCHEDULER is used to create and schedule the job.

Also Read: 5 Ways Intelligent Automation Helps Your Business Grow Faster

15. What Are Some Best Practices for Optimizing PL/SQL Code for Performance, Particularly with Large Datasets?

Optimizing PL/SQL code for performance, especially with large datasets, is essential to ensure efficient database operations. Here are some best practices:

1. Avoid Using Cursors When Possible: Cursors are often slower than bulk operations. Instead, use BULK COLLECT and FORALL to fetch and process large datasets efficiently.
2. Minimize Context Switches: There's an overhead every time you switch between SQL and PL/SQL. Try to perform as many operations as possible within SQL or PL/SQL, but avoid excessive context switches.
3. Use Efficient Joins and Indexing: Ensure your queries use proper indexes and avoid unnecessary joins that may increase the query execution time.
4. Limit the Data Retrieved: Use WHERE clauses to limit the data retrieved from tables. Fetch only what's necessary for the task.
5. Use PL/SQL Collections for Intermediate Processing: For intermediate processing of large datasets, use PL/SQL collections (like arrays, nested tables, and varrays) to store and process data in memory rather than repeatedly querying the database.
6. Parallel Processing: Consider using parallel queries or partitioning tables to spread the load in scenarios involving large data volumes.

Mastering these advanced PL SQL interview questions equips you to handle complex database tasks, troubleshoot efficiently, and design scalable solutions.

Also Read: Top 27 SQL Projects in 2025 With Source Code: For All Levels

Now that you've gained a deeper understanding of it, let's discuss some quick tips to help you excel in the interviews!

Key Tips to Succeed in Your PL/SQL Interviews

PL SQL interview questions are a blend of theoretical and practical scenarios, often designed to assess both your understanding of database concepts and your ability to apply them. 

To truly stand out, you need to demonstrate both. Here are five unique and practical tips to help you succeed:

1. Focus on Problem-Solving Over Memorization

Interviewers often look for how you approach a problem, not just if you can recall facts. When faced with a technical question, think aloud. Walk through your thought process, even if you're not immediately sure of the perfect answer. 

Breaking down the problem step by step shows that you can think critically and logically, which is more important than memorizing solutions.

2. Showcase Real-World Experience with Examples

Instead of giving textbook answers, illustrate your points with examples from real-world scenarios, even hypothetical ones. Talk about challenges you've faced with large datasets, error handling, performance tuning, or handling complex business logic. 

Interviewers appreciate when candidates can draw parallels between interview questions and actual problems they've solved.

3. Emphasize Debugging and Testing Skills

Technical proficiency alone isn't enough; demonstrating debugging skills is crucial. Be prepared to discuss how you've debugged complex PL/SQL code in the past. 

Tip: For debugging questions, explain the tools you would use and walk through the steps of identifying and fixing a performance bottleneck or a logical error in a PL/SQL block.

4. Understand Edge Cases and Limitations

PL/SQL is powerful, but it comes with certain limitations. Show that you are aware of these limitations, such as restrictions on DDL statements inside PL/SQL blocks, the mutating table error, or the performance impact of cursors in large datasets. 

Acknowledging edge cases demonstrates depth of knowledge and maturity in programming.

5. Be Ready to Optimize Your Code on the Spot

In many PL/SQL interviews, you'll be asked to write code under time constraints. After providing your initial solution, be ready to optimize it. Discuss possible improvements, such as refactoring your code for better performance or readability. 

Tip: If asked to write a simple PL/SQL block, try to mention how you'd improve it for performance after your initial solution (e.g., adding error handling, optimizing loops, or eliminating unnecessary database calls).

By following these tips, you'll not only answer the questions effectively but also leave a lasting impression by showing your problem-solving abilities.

How Can upGrad Help You Strengthen Your PL/SQL Skills and Career?

When it comes to advancing your PL/SQL skills and career, upGrad is your ultimate learning partner. With over 10 million learners worldwide, upGrad offers programs and resources that serve both beginners and seasoned professionals.

Here are a few great courses that will complement your knowledge:

• Case Study using Tableau, Python and SQL
• Learn Basic Python Programming
• Analyzing Patterns in Data and Storytelling
• Data Structures & Algorithms

Need help with where to start? Get personalized career counseling with upGrad experts who will guide your career path, or visit your nearest upGrad center and start hands-on training today! 

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