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  • Hello there, my name is Richard McMunn from the interview training company PassMyInterview.com.

  • 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 knowWhat 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 youve 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 theMyaspect

  • 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 isTEAM’. You know, the personality we

  • want to portray is of a ‘can do attitudewhere 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 asrelational’, 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