---
title: "PLSQL Complex Interview Questions (Part 2)"
description: "PL/SQL interview questions with answers given in sequence so that you can revise the subject from your mobile phone or desktop."
url: https://srinimf.com/2013/12/12/plsql-difficult-questions/
date: 2013-12-12
modified: 2026-10-10
author: "Srini"
image: https://i0.wp.com/srinimf.com/wp-content/uploads/2013/12/pexels-photo-5356421.jpeg?fit=1880%2C1058&ssl=1
categories: ["PL/SQL"]
tags: ["PL/SQL Interview Questions"]
type: post
lang: en
---

# PLSQL Complex Interview Questions (Part 2)

Here [interview questions](https://srinimf.com/2015/04/22/plsql-interview-questions-part-1/) in PL SQL and helpful for interviews and projects too.

## Interview Questions in PL SQL

1.**What is mutating table error?**

For a trigger, it is the table on which this trigger is defined. If a trigger tries to read or modify such a table, it causes a mutating table error.

2. **What is compound trigger?**

It is a solution for Mutating table error. Introduced in 11g

3. **What will happen if set serveroutput off?**

It will not write o/p to the screen

4. **What are labels ?**

Lables can be used in PL/SQL block to improve redability.

SET SERVEROUTPUT ON**<< find_stu_num >>**
BEGIN
DBMS_OUTPUT.PUT_LINE(‘The procedure
find_stu_num has been executed.’);
END **find_stu_num**;

5. **What is nested if?**

If within the If is called nested if.

6. **Difference between NULLIF and COALESCE ?**

NULLIF(exp1, exp2) => if both are equal it writes NULL. Else it writes first 1 & COLAESCE(exp1,exp2…) => It writes first non-null expression

7. **‘REVERSE’ in FOR loop?**

It iterates from higher value to lower value

8. **What is anonymous block and named block?**

Anonymous block is not stored in the server. So we can not re-use it. Named block we can use it later.

9. **FOR UPDATE and WHERE CURRENT OF ?**

The FOR UPDATE and WHERE CURRENT OF syntax can be used with cursors that are performing a delete as well as an update.

10. **How many pkgs oracle is having?**

More than 130 pkgs.

Related articles

- [PL/SQL – Complex Queries (Job Interviews)](http://srinimf.com/2013/12/08/plsql-complex-queries-job-interviews/) (srinimf.com)
- [Trigger for insert after](http://stackoverflow.com/questions/20128089/trigger-for-insert-after) (stackoverflow.com)

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