And in this training video, I'm going to teach you how to pass a SQL interview. In particular,

I'm going to give you a number of SQL interview questions and top-scoring answers. In fact,

I'm going to go through 23 SQL common interview questions; the ones I feel are most likely

to come up during your interview. I will give you the answers to those as well. I'm going

to cover both technical SQL interview questions and non-technical interview questions. And

as I say, these are the questions that I believe will come up during your interview. So, please

do stick around and watch it from beginning to end. Now, I want to stress that this interview

training video is suitable for all SQL related job roles. So, it does not matter which role

you are being interviewed for, I believe it will make a big difference to your preparation.

Now, before I get into those 23. SQL interview questions and answers, a very warm welcome

to this training tutorial. My name is Richard McMunn. That's me there in the center. I've

been helping people for about 20 years now to successfully pass their interviews, and

I do that by always giving you top-scoring answers. Please, to make sure you SUBSCRIBE

to this channel by clicking the red button below the video. Then you won't miss out on

any of the training videos I'm uploading. And I would also very much appreciate your

support if it gave the video a thumbs up (cheers!) That always motivates me to create more content

for you. Thank you very much. Also, if you want me to create a video for you that is

based on your particular job role, please tell me the name of that particular job interview

that you have coming up in the comments section below, and I will come on and create a video

for you or even give you some tips, some more tips for helping you to pass. Let's get into

those 23 SQL interview questions and answers. Now, as I said at the beginning, I'm going

to walk through 23 technical and non-technical SQL interview questions to make sure you are

fully prepared for your interview because of course, you are going to get asked questions

such as tell me about yourself. What can you bring to the role? What personality can you

bring? Why do you want to leave your current job, etc. etc. There are 23 to work for. You

can either take notes as I progress, or I will tell you where you can download these

slides to help you during your preparation as I progressed through the tutorial. The

first question of our SQL interview: Tell me about yourself and why you want this position?

We want to make sure we get off on a positive footing for this first interview question.

Here is my suggested answer. “I am a strong team worker who can be relied upon to carry

out my technical duties with passion and professionalism to ensure the goals of the department and

the company I am working for are met. My level of SQL technical ability is a strong match

for this role and I have experience of working with other developers, engineers and also

third-party service providers to compete tasks successfully. I want this SQL position because

I feel I can contribute to the team positively; I can bring something new in terms of my competence,

and you are also an attractive employer to work for due to your future plans and also

the reputation you have within the industry.” So, that's a strong answer. It puts you across

in a positive light in response to this first SQL interview question. Question number two:

So a very basic question, which you will obviously understand and know…What is SQL? Here is

my answer. “Structured Query Language, more commonly known as SQL, is seen as the standard

for managing data kept in relational database management systems. For example, SQL statements

are used to carry out tasks including updating the data, and also retrieving specific data

from a database.” Question number three: Why do you want to work for our company in

this SQL position? So again, this is a guaranteed question to come up. A lot of people want

to know why you’ve chosen their company. And, you know, a lot of people will go to

companies for the salary or because it's just convenient. But they want to know exactly

why you want to work for their company in this SQL position. Here is my suggested answer

for you: “Within any SQL job, it’s really important to choose your employer carefully.

What I mean by this is, in order to carry out your job properly, you need to work as

part of a team that has clearly defined goals, sets high standards and also works collaboratively

to achieve all company objectives. From what I found during my research into your organization,

you are very well thought of by other people who work within the industry, you have exciting

and ambitious plans for the future, and it is clear you give your staff the support they

need to grow and develop within their roles.” That's a good answer to that question, which

as I say, is going to come up during your interview. Question number four: What is MySQL?

“MySQL is an open-source relational database management system that is based on SQL, most

commonly used for web databases. It was co-founded by Michael Widenius and the ‘My’ aspect

of MySQL is the name of his daughter. The remainder is obviously an abbreviation for

Structured Query Language. MySQL is utilized by a variety of database-driven web applications.

These include WordPress and Joomla amongst others. It is also used by many of the world’s

most popular websites, including YouTube, Facebook and Twitter. Written using C and

C++ languages, MySQL supports the major platforms you’d expect such as macOS, Linux, and Windows.”

By the way, if you want to connect to me on LinkedIn.com, I'm sure you are probably on

LinkedIn, I have put my LinkedIn description, my LinkedIn link, sorry, in the description

below the video, so you can connect with me and say hello. Question number 5. What's the

main difference between SQL and MySQL? “So, SQL is often used to access, manipulate and

update the data within a database, whereas MySQL is a relational database management

system that keeps the data within the database organized. In other words, SQL is a language

created to manage relational databases, and MySQL is an open-source relational database

management system, based on SQL.” Question number 6: In SQL, what are joins? “There

are four main types of joins in SQL. These are FULL JOINS, RIGHT JOINS, LEFT JOINS and

INNER JOINS. Joins basically combine the rows from two or more tables.” Question 7: What

is an index and why is it useful to have? “An index is useful because it allows for

the faster retrieval of records from a table. The index creates an entry for each value,

which in turn, makes it much faster to retrieve the data required, or in other words, an index

is a pointer to data contained within a table.” Question number 8. What personality will you

bring to the team? So, they are assessing here what kind of person you are. You might

have immense technical ability; however, your personality might be of someone who just wants

to crack on, on their own. The key word here is ‘TEAM’. You know, the personality we

want to portray is of a ‘can do attitude’ where you will help the team to achieve their

objectives. And that is the kind of answer I suggest you give! Here is my suggested answer

to, what personality will you bring to the team? “My personality is one of always being

positive, having a can-do attitude and also being supportive of other developers, team

members and ensuring I help out the team in a professional and timely manner. What’s

important within any SQL role, is to remember you are all working together collaboratively

to achieve the company’s objectives, and on that basis, you have to bring your technical

expertise to the table, look for efficient ways of working, and also respond to people’s

queries and questions in as quick a time as possible.” So that would be attractive to

any organization, any hiring manager. If you said that's the kind of personality that you

have, that's positive in nature, but you've also got the technical level of expertise.

Next question: If a constraint is added in SQL, what does this mean? “There are many

different types of SQL constraints which can be used. Their purpose is to specify a rule

for the data within a table, limiting the type of data that can go within the table.

The constraint can be added either during the creation of a table, or once it has been

created. Constraints can be applied to either the table as a whole or column level.” Question

number 10: What are the more common types of SQL constraint and what do they mean? Here

is my answer. “There are several common SQL constraints. These are PRIMARY KEY, which

identifies each record in a table; NOT NULL is used to prevent a NULL value being inserted

into a column; FOREIGN KEY, which provides a unique identification of a row or record

within another table; and also DEFAULT, which will automatically assign a default value

if there has not been a value already specified for a field. There is also CHECK, which is

a constraint that is used to verify that all values meet a specific criteria or condition

in a field; and UNIQUE, which ensures unique values are always inserted into a column.

Finally, INDEX is used to create data and to obtain it from a database with speed.”

Question 11: So far, you have referred to tables and fields in your answers. What are

they? “In its simplest form, a TABLE is a collection of data that is organized into

rows and columns. The columns are vertical, and the rows are horizontal. The columns are

called FIELDS and the rows are often referred to as records.” Don't forget, I am going

to tell you at some stage soon where you can download these slides and you can use them

during your preparation. Question 12. What's your biggest weakness? So, this is a difficult

one, because we don't want to give them a weakness that will prevent you from getting

the job. My suggested answer for the weakness interview question is to say sometimes you

find it hard to strike a healthy work life balance, because you're always committed,

always working, perhaps you are somebody who is prepared to do loads of work in the evening

and your partner doesn't like it. Something like that. Here is my answer. “My biggest

weakness is that I find it difficult to say no to people, and I end up taking on way too

many tasks than I can handle at times. In the past, because of my reluctance to say

to no to work, I've ended up working literally all weekend just to catch up. Whilst I will

always say yes to work, I am learning to manage my workload more effectively, and prioritize

what needs to be done for my employer.” That is a smart answer, because you are demonstrating

that you will take on loads and loads of work, but you are becoming more smarter at managing

your workload. Question 13: Tell me what the different subsets of SQL are? “So, there

are three main subsets of SQL. Firstly, there is Data Control Language, or DCL, which permits

you to control access to the database. For example, you can either grant access to the

database or revoke it. Then there is DDL, which is Data Definition Language, which allows

you to specify data structures in the database, including deleting tables, creating them or

altering them. Finally, there is Data Manipulation Language (DML) which, as the name suggests,

allows you to manipulate the data, including updating, inserting, deleting or retrieving

data in the table as required.” Question 14: Here is a situational type interview question.

It's 5 p.m. on a Friday and you receive a request from a stakeholder who says it's urgent.

You assess the task and it will take approximately one hour to complete. What would you do? Well,

I'd tell them I'm not going to do it. I'm going home! No, I'm joking! You can't say

that. So, because it's 5 o'clock on a Friday afternoon, that's a sort of hint in the question...

they are looking for somebody who is going to hopefully stay behind and do the work!

Here is my suggested answer. “I would start off by clarifying what their exact requirements

were before setting to work on the task to get it completed before I went home for the

weekend. I think in those types of situations, it’s easy to say you can’t do it because

it’s late on a Friday afternoon, but this is an opportunity to show how flexible we

are as an organization and to also provide great service by going above and beyond what

would normally be required. My personal life is flexible, so I would certainly be available

to stay behind and get tasks like these complete for the stakeholder.” That shows that you

are putting the team and the organization first, which is very important in any SQL

related role. Question 15. How would you format SQL server dates? So, how would you format

SQL server dates? “For this, the FORMAT function can be used. This function allows

the formatting of the date and time. Firstly, I would decide what format I wanted, for example

DD/MM/YYYY or MM-DD-YY. If I wanted to get DD/MM/YYYY I would use SELECT FORMAT (getdate(),

'dd/MM/yyyy’).” Question 16: What is primary and foreign key? “For a database table to

qualify as ‘relational’, it needs to have a primary key. A primary key has one or more

columns. The data within the columns is then used to identify each row in a table. Basically,

these are very similar to street addresses, for example. So, if you think of the rows

in the table as the dustbins or trashcans belonging to houses on a street, the primary

key is the list of the addresses. Primary key attributes cannot have NULL values. A

foreign key is a column in one table. In that table, the values are members of a primary

key column in another table. It is possible for a foreign key attribute to accept NULL

values and for there to be more than one foreign key in a table.” Question 17: Why do you

want to leave your current job? Why are you leaving your job and why do you want to work

for us? Here we go. “I want to leave my job because I am looking for a fresh challenge

with a company that has exciting and ambitious plans for the future, and one that will also

use my skills and technical SQL abilities to the full. My employer has been great and

we have achieved some fantastic things whilst I have been there, but I am now ready for

a new challenge, and I would like that challenge to be with your company.” A hint there is

never be disrespectful to your former employer. Don't be critical of any bosses or your work

colleagues. Always be positive. Say you're ready for a new challenge where, I suggest,

your skills are going to be used to great use. Question 18: What is database denormalization?

“Denormalization is a method used to improve the performance of a database, allowing the

retrieval of data in the quickest time possible. Essentially, the process of denormalization