PL/SQL Interview Questions- Part 7

PL/SQL Interview Questions- Part 7

PL/SQL is one of the most in-demand skills for professionals working with Oracle databases. It allows you to create powerful programs that automate business logic and manage large amounts of data efficiently.

In job interviews, candidates are often evaluated on their ability to write clean, reusable PL/SQL code. Topics like exception handling, control structures, stored procedures, and performance tuning are common. That’s why we’ve put together this collection of top PL/SQL interview questions and answers to help you prepare.

These questions are carefully selected to help you understand key concepts and demonstrate your skills in a clear and structured way. Whether you’re preparing for your first job or looking to switch roles, this guide will help you approach interviews with more confidence. Read through each question, practice your responses, and stay ready for anything the interviewer might throw your way.

Answer:

The following are some considerable differences between the Nested Tables & Varrays:

Nested Tables

  • Nested tables don’t have any limits & are unbounded.
  • They are initially dense but can become sparse through the deletion of elements.
  • Orders are not preserved in the Nested Tables.
  • Nested Tables can be indexed.

Varrays

  • Varrays always have a limited number of elements as they are bounded.
  • They never become sparse.
  • When you retrieve & store a VARRAY, its element order is preserved.
  • Varrays cannot be indexed.

Answer:

You can consider temporarily disabling a database trigger in case any of the following is true:

  • An object that a trigger reference isn’t available.
  • You need to execute a large data load & want it to quickly proceed without the firing triggers.
  • You are loading data into a table to which the trigger applies.

Answer:

Triggers use Conditional Predicates like UPDATING, INSERTING, and DELETING to decide which particular event will cause a trigger to fire. All three predicates have Boolean values and are useful in triggers like AFTER INSERT or UPDATE.

Answer:

You can use the IN OUT parameter mode to initialize a parameter in the procedure, as any value can be initially assigned to the IN OUT parameter when the procedure is called from a calling environment. The IN OUT parameter’s value can be changed when executing a procedure & the result is then returned back to a calling environment from the procedure.

Answer:

Function purity levels mean what type of data structures can be modified or read by a function. There are four types of function purity levels as follows:

  • WNDS: It writes no database state & does not modify a database table with any DML statement.
  • RNDS: It reads no database state & any database tables with the SELECT statement.
  • WNPS: It writes no package state & does not modify any packaged variables.
  • RNPS: It reads no package state & does not read any packaged variables.