PL/SQL Interview Questions
PL/SQL is a procedural language extension to SQL that adds
control structures, loops, and other programming constructs. It is used in
Oracle Database and other database servers. Questions that are commonly asked
in interviews for PL/SQL positions include: What is the difference between SQL
and PL/SQL?What are some of the features of PL/SQL?What are some of the
benefits of using PL/SQL?What are some of the drawbacks of PL/SQL?How can
PL/SQL be used in Oracle Database?PL/SQL is a procedural language extension to
SQL that adds functionality such as conditional branching, looping and
It is commonly used in database programming, and can be
embedded in other languages such as C and Java.The most important thing to
remember when preparing for a PL/SQL interview is that the interviewer is
looking for your ability to think logically and solve problems. They will often
give you a scenario and ask you how you would approach it. Other questions may
test your knowledge of the language syntax or specific features.PL/SQL is a
procedural language extension to SQL that adds functionality such as looping,
branching, and other programming constructs. It is one of the most popular
languages used by developers working with Oracle databases.If you're preparing
for a PL/SQL interview, you may be wondering what sorts of questions you'll be
Here are some sample questions that will give you an idea of
the types of things you'll need to know:What are some of the differences
between PL/SQL and other programming languages?How can PL/SQL be used in
application development?What are some guidelines for efficient PL/SQL
programming?What are some common errors made when programming in PL/SQL?What
are some best practices for debugginPL/SQL is a procedural language extension
to SQL that adds functionality such as looping, decision making, and exception
handling. PL/SQL is not a standalone language, but rather an extension of SQL.
In order to write PL/SQL code, you must have a basic understanding of SQL.The
most common PL/SQL interview questions revolve around the topics of cursors,
stored procedures, and functions. You should be prepared to answer questions
about these topics, as well as general questions about PL/SQL syntax and usage.
1. What is PL/SQL, and what are its advantages?
Answer: PL/SQL stands for Procedural
Language/Structured Query Language. It is an extension of SQL that allows
developers to write procedural code, making it more powerful and flexible than
regular SQL. The advantages of PL/SQL include improved performance, better code
organization through procedures and functions, enhanced security, and reduced
2. Differentiate between a stored procedure and a
function in PL/SQL.
Answer: The main difference between a stored
procedure and a function in PL/SQL lies in their return values. A stored
procedure does not return a value, while a function always returns a value.
Functions are used when you need to compute and return a single value, whereas
procedures are used for executing a series of SQL statements or tasks without
returning a value.
3. Explain the EXCEPTION block in PL/SQL and its
Answer: The EXCEPTION block in PL/SQL is used
for handling errors or exceptions that may occur during the execution of a
block of code. When an exception occurs, the control is transferred to the
EXCEPTION block, and appropriate error handling can be implemented. It ensures
that the program continues to execute gracefully even in the presence of
errors, maintaining the integrity of the application.
4. How do you declare variables in PL/SQL?
Answer: In PL/SQL, you can declare variables
using the "DECLARE" keyword within a block. The syntax for declaring
variable_name data_type [NOT NULL] [:=
-- PL/SQL code
5. What is a cursor in PL/SQL, and why is it used?
Answer: In PL/SQL, a cursor is a mechanism used
to process individual rows returned by a SQL query. It allows developers to
retrieve and manipulate data row by row within a loop. Cursors are used when
you need to perform operations on each row of the result set sequentially.
6. Discuss the use of triggers in PL/SQL.
Answer: Triggers in PL/SQL are special types of
stored programs that are automatically executed when certain database events
occur, such as insert, update, delete, or database startup/shutdown. They are
useful for implementing business rules, data validation, and maintaining data
7. How do you handle exceptions in PL/SQL?
Answer: Exception handling in PL/SQL is achieved
using the "EXCEPTION" block. It allows developers to catch specific
errors and take appropriate actions, such as logging the error or displaying a
user-friendly message. The EXCEPTION block contains the error-handling code and
ensures the program continues execution, even if an exception occurs.
8. Explain the difference between "BEFORE" and
Answer: In PL/SQL, "BEFORE" triggers
are fired before the event (e.g., insert, update, delete) occurs, while
"AFTER" triggers are fired after the event has occurred.
"BEFORE" triggers are commonly used for data validation, and
"AFTER" triggers are often used for logging or auditing purposes.
9. How can you pass parameters to a stored procedure or
Answer: Parameters can be passed to a stored
procedure or function by including them within the parentheses when creating
the procedure or function. These parameters act as placeholders for values that
will be provided when the procedure or function is called.
10. What is the purpose of the COMMIT statement in
Answer: The COMMIT statement in PL/SQL is used
to permanently save any changes made to the database during a transaction. It
makes the changes permanent and releases any locks held on the affected data.
If the transaction is successful, the COMMIT statement should be executed to
make the changes permanent.
11. Describe the concept of "PRAGMA
AUTONOMOUS_TRANSACTION" is a PL/SQL pragma that allows a procedure or
function to execute as a separate transaction independent of the calling
transaction. It is often used when you need to perform actions that are not
dependent on the outcome of the calling transaction.
12. How do you use collections in PL/SQL?
Answer: Collections in PL/SQL are used to store
multiple values in a single variable. There are three types of collections:
associative arrays (also known as index-by tables), nested tables, and VARRAYs
(variable-size arrays). Collections are useful for processing bulk data and
performing operations on multiple values simultaneously.
13. Explain the usage of the "FORALL" statement
Answer: The "FORALL" statement in
PL/SQL is used for bulk processing of data using collections. It allows you to
perform a single DML (Data Manipulation Language) operation on multiple rows at
once, improving the efficiency of data processing.
14. Discuss the benefits of using "BULK
COLLECT" in PL/SQL.
Answer: "BULK COLLECT" is a feature in
PL/SQL that allows developers to fetch multiple rows of data from a query into
a collection variable in a single database call. It significantly improves the
performance of data retrieval and manipulation operations, especially when
dealing with large data sets.
15. How can you debug PL/SQL code effectively?
Answer: PL/SQL provides several debugging
techniques, such as using the "DBMS_OUTPUT.PUT_LINE" procedure to
print messages during code execution, setting breakpoints in integrated
development environments (IDEs), and using tools like Oracle SQL Developer for
advanced debugging and profiling.