Oracle SQL Interview Questions To Land That Job!

oracle sql interview questionsGet That Job in SQL for Oracle!

So you have been introduced to and have learned the basics of using the SQL language on a Oracle database and are pondering what your next step may be –  well, getting a job of course!  After learning how to set up your Oracle environment, the basic terminology of SQL, and overall becoming a master of SQL on the Oracle database, now comes the fun part: job hunting and getting prepared for your SQL interview.  Don’t you worry…we are to guide you step-by-step through your interview process. Oracle SQL questions are obviously extremely important during your job interview and the interviewer will no doubt test your confidence in your knowledge. Although you have the technical  savvy and know how, the interview process is a healthy combination of expertise and personality. There are courses that will help you with this combination and grow not only your interviewing skills, but vastly improve your resume and networking abilities.  From becoming fluent in SQL language, to mastering the interview process, to finally, learning a way to combine the two, we will show you how.  Final destination: a job related to your knowledge of SQL language in the Oracle database.

The Basics For Interview Taking

It doesn’t matter if you are a master of the SQL universe- knowing the basics of interview taking are vital in getting any job that truly matters to you. As we all know, job interviews are always stressful and nerve wracking – even for those with the most knowledge in their specific field.  The best way to reduce the anxiety and stress of the interview process is preparation.  Interviewers can immediately tell who enters a job interview prepared and also, those that do not (don’t let that be you).  First off, lets go over the essentials in any interview process and what to be prepared for:

Questions regarding your work history

While these questions may seem harmless and easy enough, this is a prime opportunity to sell not only yourself, but what led into your current interest and newly (or not) acquired skill set in SQL. Since this is your own personal history of sorts, be prepared to explain in detail  what your prior jobs entailed, any awards or praise garnered and especially how you grew from your time there. Also, be prepared for the dreaded question: “What was your reason for leaving?” Cringe. Do not be hesitant in flaunting some of your own training and continued education in SQL -even if you learned from scratch.   Also, be ready to answer what you enjoyed/didn’t enjoy at your previous jobs, your biggest accomplishments/failures, problems encountered at work and how you yourself were able to solve them, your ability to work with managers and coworkers, what could have been done differently at your prior workplace, and any managerial or training experience.  Walking in with a prepared mindset goes a long way and understanding that these questions (and maybe some you might not expect) may be asked, is a way to alleviate and conquer your pre-interview jitters.

Questions About You

In this age of the selfie, who doesn’t like talking about themselves? Questions at this stage are basically about what you bring to the table and also how you are a better candidate from everyone else who is applying –  especially with your expertise in SQL for Oracle.  In a job market that seems to get more and more competitive,  differentiating  yourself proves vital  as you rise above the applying herd.  Arguably the most integral part of all your interview skills is the ability to successfully sell yourself.  Here is a list of questions that you must prepare for if you hope to land that well deserved job:

  • What is your greatest weakness?
  • What is your greatest strength?
  • How well do you work with others?
  • Are you able to leave personal issues at the door?
  • Do you take work home with you?
  • How do you handle pressure? Stress?
  • What are your dreams? Fears?
  • Are you a self-motivator?
  • Do you prefer to work independently or on a team?
  • Describe a time when your workload was heavy and how you handled it.

While this list is far from complete, it provides a strong base for any questions directed your way. Answered without hesitation (and hopefully practice beforehand), your confidence and preparation will undoubtedly shine through.  Now that you are ready to interview for seemingly any position, lets make this more specific and focus toward your expertise in SQL for Oracle.

Specific Questions For SQL for Oracle

Now that you are comfortable with your newly acquired knowledge of the interviewing process, now it is time to get ready for the specific Oracle SQL interview questions you may be asked. Here are our top 8:

What are Joins and Types of Join?

To make any result complete, we need to retrieve data from two or more tables. This is called a join.

Types of join:

INNER JOIN

This join returns rows when there is at least one match in both the tables.

OUTER JOIN

There are three different Outer Join methods:

1. LEFT OUTER JOIN

This join returns all the rows from the left table with the matching rows from the right table. If there are no fields matching in the right table then it returns NULL values.

2. RIGHT OUTER JOIN

Right outer join returns all the rows from the right table with the matching rows from the left table. If there are no field matching in the left table then it returns NULL values.

3. FULL OUTER JOIN

Full outer join merges the left outer join and right outer join.  This returns the row from either table when the conditions are met and returns null value when there is no match

4. CROSS JOIN
This is an operation that produces the Cartesian product of two tables. Unlike other JOIN operators, it does not let you specify a join clause. However, you can specify a WHERE clause in the SELECT statement.The output result contains records that are multiplication of records from both the tables.

If a brush up on the importance or how any specific join works, a revisit with the fundamentals of SQL for Oracle may prove highly beneficial.

What is the difference between LEFT, RIGHT, and OUTER Joins?

If there are any values in one table that do not have corresponding values in the other, that row will not be selected.  Such rows can be forcefully selected by using the outer join symbol (+) on either of the sides (left or right) based on the requirement.

What are set operators?

UNION, INTERSECT or MINUS are called SET OPERATORS.

What are the different datatypes supported by sql in oracle?

Char (size), Nchar (size), Varchar2 (size), Nvarchar2 (size) data types for character values, Number (precision, scale), Number, Number (n), Float, Float (binary precision) data types for numerical values, Date data type for date values, Long, Raw (size),  Long Raw,  Clob, Blob, Nclob, Bfile for large objects.

What is the difference between LONG and LOB datatypes?

LOB

  • Maximum size is 4GB
  • Can be attributes of an object type (except NCLOB)
  • Support random access to data
  • Multiple LOB columns per table or LOB attributes in an object type

LONG

  • Maximum size is 2GB
  • Cannot be be attributes of an object type
  • Support only sequential access
  • Only one LONG column is allowed in a table

How much memory is allocated for date datatype? What is the defaault date format in Oracle?

Date datatype in Oracle allocates 7 bytes of memory.  The default date format is DD-MON-YY.

What is a constraint? What are its various levels?

Constraints are restrictions set to the column to enforce data entity and consistency.  There are 2 levels:

  1. Column level constraints
  2. Table-level constraints

List all constraints supported by Oracle

Primary Key, Foreign Key or Referential Integrity, Not Null, Unique, and Check.

Again, this list is far from complete, but provides a valuable starting point for any positions that demand an SQL knowledge for Oracle.  Feel as if these terms are foreign or simply need a refresher? You can learn by example or dive in to more advanced courses offered by Udemy before your interview.  Remember to smile, make eye contact, shake hands firmly, and flaunt your mastery over Oracle SQL Interview Questions. Oh, and also – don’t forget to thank us after you hear those two glorious words: “you’re hired.”