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Top 20 sql queries interview questions 
and answers 
If you need top 7 free ebooks below for your job interview, please vi...
Tell me about yourself? 
This is probably the most asked 
question in sql queries interview. It 
breaks the ice and gets y...
What is the difference between “delete” , 
“truncate” and “drop” commands 
Delete Command : Delete Command 
Belongs to DML...
What Can You Do for Us That Other Candidates 
Can't? 
What makes you unique? This 
will take an assessment of 
your experi...
What is the difference between primary key and 
unique key 
Unique Key: 
a.A table can contain more than one 
unique key 
...
What is the difference between sub queries and 
joins 
a.Sub Queries : 
To write sub queries between two or 
more tables, ...
Write syntax for views and stored procedures 
View Syntax: 
Create view <view-name> as select 
<column names> from <table-...
What are the different constraints available in 
sql and Explain 
Not Null -> enforces a column to 
Not accept Null values...
By default how the column data would display if 
use order by <column> 
By default the order by would display 
the data in...
What is the operator in sql to find pattern match 
Like 
Select <colnames> from <table-name> 
where <col> like <pattern> 
...
What is the purpose of ‘distinct’ in sql 
Distinct is used to display only the 
different values 
Ex: 
Select distinct <co...
What is the difference between union and union 
all 
The UNION operator selects only distinct 
values by default. To allow...
How can I find total number of employees with 
more than 40 years? 
SELECT 
COUNT(EMPLOYEES.*) FROM 
EMPLOYEES 
WHERE EMPL...
How to create Identity Column using Query? 
SELECT 
row_number() OVER(ORDER by 
TESTTABLE.p1) as SRNO, 
result=CASE 
WHEN ...
How do I select 2nd highest salaried employee 
from my EMPLOYEE table? 
SELECT 
EMPLOYEE.*, 
MAX(EMPLOYEE.Salary) AS 
Sala...
How to select top 3 employees from EMPLOYEE 
table which is grouped in the salary groups? 
SELECT 
EMPLOYEE.* 
FROM 
(SELE...
How to find all the employees from EMPLOYEE 
table who earns more than the average salary of 
their department 
SELECT 
OU...
How to list employees with period of service in 
terms of years and months? 
SELECT 
EMPLOYEE.*,TO_CHAR(TRUNC( 
MONTHS_BET...
How to display only Even Records from 
EMPLOYEE table? 
SELECT 
EMPLOYEE.* 
FROM EMPLOYEE 
WHERE (rowid,0) in 
(SELECT row...
How to display only Odd Records from 
EMPLOYEE table? 
SELECT 
EMPLOYEE.* 
FROM EMPLOYEE 
WHERE (rowid,1) in 
(SELECT rowi...
What are DDL and DML commands? 
DDL (DataDifinition Language): 
Create 
Alter 
Truncate 
Drop 
DML (Data Manipulation 
Lan...
Useful job interview materials: 
If you need top free ebooks below for your job interview, please visit: 
4career.net 
• F...
Top 6 tips for job interview 
Interview questions and answers – free pdf download Page 23 of 29
Tip 1: Do your homework 
You'll likely be asked difficult questions 
during the interview. Preparing the list of 
likely q...
Tip 2: First impressions 
When meeting someone for the first time, we 
instantaneously make our minds about various aspect...
good-first-impression-at-a-job-interview 
Tip 3: The “Hidden” Job Market 
Many of us don’t recognize that hidden job 
mark...
Tip 4: Do-It-Yourself Interviewing Practice 
There are a number of ways to prepare 
for an interview at home without the 
...
Tip 5: Ask questions 
Do not leave the interview without 
ensuring that you know all that you 
want to know about the posi...
Tip 6: Follow up and send a thank-you note 
Following up after an interview can 
help you make a lasting impression and 
s...
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Top sql queries interview questions and answers job interview tips

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You'll likely be asked difficult questions during the interview. Preparing the list of likely questions in advance will help you easily transition from question to question.

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Top sql queries interview questions and answers job interview tips

  1. 1. Top 20 sql queries interview questions and answers If you need top 7 free ebooks below for your job interview, please visit: 4career.net • Free ebook: 75 interview questions and answers • Top 12 secrets to win every job interviews • 13 types of interview quesitons and how to face them • Top 8 interview thank you letter samples • Top 7 cover letter samples • Top 8 resume samples • Top 15 ways to search new jobs Interview questions and answers – free pdf download Page 1 of 29
  2. 2. Tell me about yourself? This is probably the most asked question in sql queries interview. It breaks the ice and gets you to talk about something you should be fairly comfortable with. Have something prepared that doesn't sound rehearsed. It's not about you telling your life story and quite frankly, the interviewer just isn't interested. Unless asked to do so, stick to your education, career and current situation. Work through it chronologically from the furthest back to the present. Interview questions and answers – free pdf download Page 2 of 29
  3. 3. What is the difference between “delete” , “truncate” and “drop” commands Delete Command : Delete Command Belongs to DML Can be Used to delete entire Table data Can be used to delete specific rows using where clause Can be rolled back Truncate Command: Truncate Command Belongs to DDL Can be Used to delete entire Table data Can't be used to delete specific rows using where clause Can't be rolled back Drop Command: Drop Command Belongs to DDL Can be Used to delete entire Table data and also the structure Can't be used to delete specific rows using where clause Can't be rolled back Interview questions and answers – free pdf download Page 3 of 29
  4. 4. What Can You Do for Us That Other Candidates Can't? What makes you unique? This will take an assessment of your experiences, skills and traits. Summarize concisely: "I have a unique combination of strong technical skills, and the ability to build strong customer relationships. This allows me to use my knowledge and break down information to be more user-friendly." Interview questions and answers – free pdf download Page 4 of 29
  5. 5. What is the difference between primary key and unique key Unique Key: a.A table can contain more than one unique key b.Unique key allows one null value Primary Key: a.A table can contain only one primary key (can be one/more columns) b.Primary key will not allow null values Interview questions and answers – free pdf download Page 5 of 29
  6. 6. What is the difference between sub queries and joins a.Sub Queries : To write sub queries between two or more tables, there is no need to be relation exist among those tables b.Joins: To write joins between two or more tables, there should be relation exist among those tables Interview questions and answers – free pdf download Page 6 of 29
  7. 7. Write syntax for views and stored procedures View Syntax: Create view <view-name> as select <column names> from <table-name> where <condition> Stored Procedure Sysntax: Create procedure <procedure-name> as begin select <column names> from <table-name> end Note: These are only sample examples, we can write in different ways also. Interview questions and answers – free pdf download Page 7 of 29
  8. 8. What are the different constraints available in sql and Explain Not Null -> enforces a column to Not accept Null values Unique -> uniquely identifies each record in a database table Primary Key -> uniquely identifies each record in a database table and it cannot contain NULL values. Foreign Key -> A Foreign Key in one table points to a PRIMARY KEY in another table. Check -> It is used to limit the value range that can be placed in a column. Default -> It is used to insert a default value into a column. Interview questions and answers – free pdf download Page 8 of 29
  9. 9. By default how the column data would display if use order by <column> By default the order by would display the data in ascending order Syntax: a. select <col-names> from <table-name> order by <col-names> It will display the results in ascending order select <col-names> from <table-name> order by <col-names> desc It will display the results in descending order select <col-names> from <table-name> order by <col-names> asc It will display the results in ascending order Interview questions and answers – free pdf download Page 9 of 29
  10. 10. What is the operator in sql to find pattern match Like Select <colnames> from <table-name> where <col> like <pattern> Ex: a. Select ename from emp where ename like ‘v%’ It will display all the names which are start with ‘v’ b. Select ename from emp where ename not like ‘v%’ It will display other than all the names which are start with ‘v’ Interview questions and answers – free pdf download Page 10 of 29
  11. 11. What is the purpose of ‘distinct’ in sql Distinct is used to display only the different values Ex: Select distinct <col-names> from <table-name> Select distinct ename from emp Interview questions and answers – free pdf download Page 11 of 29
  12. 12. What is the difference between union and union all The UNION operator selects only distinct values by default. To allow duplicate values, use UNION ALL Select <col-names> from <table1> union select <col-names> from <table2> Select <col-names> from <table1> union all select <col-names> from <table2> Interview questions and answers – free pdf download Page 12 of 29
  13. 13. How can I find total number of employees with more than 40 years? SELECT COUNT(EMPLOYEES.*) FROM EMPLOYEES WHERE EMPLOYEES.Age>40 Interview questions and answers – free pdf download Page 13 of 29
  14. 14. How to create Identity Column using Query? SELECT row_number() OVER(ORDER by TESTTABLE.p1) as SRNO, result=CASE WHEN TESTTABLE.p1 IS NOT NULL THEN TESTTABLE.p1 WHEN TESTTABLE.p2 IS NOT NULL THEN TESTTABLE.p2 END FROM TESTTABLE Interview questions and answers – free pdf download Page 14 of 29
  15. 15. How do I select 2nd highest salaried employee from my EMPLOYEE table? SELECT EMPLOYEE.*, MAX(EMPLOYEE.Salary) AS SalarySecondHighest FROM EMPLOYEE WHERE EMPLOYEE.Salary< (SELECT MAX(EMPLOYEE.Salary) AS SalaryFirstHighest FROM EMPLOYEE) Interview questions and answers – free pdf download Page 15 of 29
  16. 16. How to select top 3 employees from EMPLOYEE table which is grouped in the salary groups? SELECT EMPLOYEE.* FROM (SELECT EMPLOYEE.*, rank() OVER(PARTITION BY EMPLOYEE.Salary ORDER BY EMPLOYEE.Salary ASC) AS Rank from EMPLOYEE ) EMPLOYEE where Rank<3 -- if you want to top n employees for each grouped salary -- replace 3 in the query with (n+1) ORDER BY EMPLOYEE.Salary Interview questions and answers – free pdf download Page 16 of 29
  17. 17. How to find all the employees from EMPLOYEE table who earns more than the average salary of their department SELECT OUTEREMPLOYEE.*, OUTEREMPLOYEE.Salary FROM EMPLOYEE OUTEREMPLOYEE WHERE OUTEREMPLOYEE.Salary > (SELECT AVG(INNEREMPLOYEE.Salary) FROM EMPLOYEE INNEREMPLOYEE WHERE OUTEREMPLOYEE.DepartmentID = INNEREMPLOYEE.DepartmentID) Interview questions and answers – free pdf download Page 17 of 29
  18. 18. How to list employees with period of service in terms of years and months? SELECT EMPLOYEE.*,TO_CHAR(TRUNC( MONTHS_BETWEEN(SYSDATE, EMPLOYEE.HireDate)/12)) AS Years, TO_CHAR(TRUNC( MOD(MO NTHS_BETWEEN(SYSDATE, EMPLOYEE.HireDate),12))) AS Months FROM EMPLOYEE Interview questions and answers – free pdf download Page 18 of 29
  19. 19. How to display only Even Records from EMPLOYEE table? SELECT EMPLOYEE.* FROM EMPLOYEE WHERE (rowid,0) in (SELECT rowid,mod(rownum,2) FROM EMPLOYEE) Interview questions and answers – free pdf download Page 19 of 29
  20. 20. How to display only Odd Records from EMPLOYEE table? SELECT EMPLOYEE.* FROM EMPLOYEE WHERE (rowid,1) in (SELECT rowid,mod(rownum,2) FROM EMPLOYEE) Interview questions and answers – free pdf download Page 20 of 29
  21. 21. What are DDL and DML commands? DDL (DataDifinition Language): Create Alter Truncate Drop DML (Data Manipulation Language): Select Insert Update Deletet Interview questions and answers – free pdf download Page 21 of 29
  22. 22. Useful job interview materials: If you need top free ebooks below for your job interview, please visit: 4career.net • Free ebook: 75 interview questions and answers • Top 12 secrets to win every job interviews • Top 36 situational interview questions • 440 behavioral interview questions • 95 management interview questions and answers • 30 phone interview questions • Top 8 interview thank you letter samples • 290 competency based interview questions • 45 internship interview questions • Top 7 cover letter samples • Top 8 resume samples • Top 15 ways to search new jobs Interview questions and answers – free pdf download Page 22 of 29
  23. 23. Top 6 tips for job interview Interview questions and answers – free pdf download Page 23 of 29
  24. 24. Tip 1: Do your homework You'll likely be asked difficult questions during the interview. Preparing the list of likely questions in advance will help you easily transition from question to question. Spend time researching the company. Look at its site to understand its mission statement, product offerings, and management team. A few hours spent researching before your interview can impress the hiring manager greatly. Read the company's annual report (often posted on the site), review the employee's LinkedIn profiles, and search the company on Google News, to see if they've been mentioned in the media lately. The more you know about a company, the more you'll know how you'll fit in to it. Ref material: 4career.net/job-interview-checklist- 40-points Interview questions and answers – free pdf download Page 24 of 29
  25. 25. Tip 2: First impressions When meeting someone for the first time, we instantaneously make our minds about various aspects of their personality. Prepare and plan that first impression long before you walk in the door. Continue that excellent impression in the days following, and that job could be yours. Therefore: · Never arrive late. · Use positive body language and turn on your charm right from the start. · Switch off your mobile before you step into the room. · Look fabulous; dress sharp and make sure you look your best. · Start the interview with a handshake; give a nice firm press and then some up and down movement. · Determine to establish a rapport with the interviewer right from the start. · Always let the interviewer finish speaking before giving your response. · Express yourself fluently with clarity and precision. Useful material: 4career.net/top-10-elements-to-make-a- Interview questions and answers – free pdf download Page 25 of 29
  26. 26. good-first-impression-at-a-job-interview Tip 3: The “Hidden” Job Market Many of us don’t recognize that hidden job market is a huge one and accounts for 2/3 of total job demand from enterprises. This means that if you know how to exploit a hidden job market, you can increase your chance of getting the job up to 300%. In this section, the author shares his experience and useful tips to exploit hidden job market. Here are some sources to get penetrating into a hidden job market: Friends; Family; Ex-coworkers; Referral; HR communities; Field communities; Social networks such as Facebook, Twitter…; Last recruitment ads from recruiters; HR emails of potential recruiters… Interview questions and answers – free pdf download Page 26 of 29
  27. 27. Tip 4: Do-It-Yourself Interviewing Practice There are a number of ways to prepare for an interview at home without the help of a professional career counselor or coach or a fee-based service. You can practice interviews all by yourself or recruit friends and family to assist you. Useful material: 4career.net/free-ebook- 75-interview-questions-and-answers Interview questions and answers – free pdf download Page 27 of 29
  28. 28. Tip 5: Ask questions Do not leave the interview without ensuring that you know all that you want to know about the position. Once the interview is over, your chance to have important questions answered has ended. Asking questions also can show that you are interested in the job. Be specific with your questions. Ask about the company and the industry. Avoid asking personal questions of the interviewer and avoid asking questions pertaining to politics, religion and the like. Ref material: 4career.net/25-questions-to- ask-employers-during-your-job-interview Interview questions and answers – free pdf download Page 28 of 29
  29. 29. Tip 6: Follow up and send a thank-you note Following up after an interview can help you make a lasting impression and set you apart from the crowd. Philip Farina, CPP, a security career expert at Manta Security Management Recruiters, says: "Send both an email as well as a hard-copy thank-you note, expressing excitement, qualifications and further interest in the position. Invite the hiring manager to contact you for additional information. This is also an excellent time to send a strategic follow-up letter of interest." Ref material: 4career.net/top-8- interview-thank-you-letter-samples Interview questions and answers – free pdf download Page 29 of 29

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