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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

  • 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

  • adds redundant database data into a table which in turn enables the performance of the

  • database to improve significantly, as the same data can be put in several places.”

  • Number 19: What is database normalization? “Normalization reduces redundancy of data

  • within a database. Normalization is a design technique that places larger database tables

  • into smaller tables and then uses specific relationships to link them. In other words,

  • normalization is the process of putting each piece of data in the appropriate place, using

  • multiple tables. The benefit is keeping data integrity and it makes updating faster, but

  • retrieval of data, can then in turn be slower.” Question 20: What are your salary expectations

  • in this SQL position? So, we need to be careful here. We don't want to devalue ourselves,

  • but then we don't want to be overconfident and arrogant, and put them off by saying we

  • want a huge amount, because remember, they don't know our capabilities at present. So

  • here is a really strong answer to this question that works for both sides: it is a win-win

  • answer. “I have carried out some research in relation to the average salary for this

  • SQL position, and the general range is between $40,000 and $48,000. Whilst I do personally

  • feel I am worth the higher end of the salary scale, I understand and appreciate I need

  • to prove to you my worth. On that basis, I would be comfortable with a salary of $45,000.”

  • What I suggest you do for your role, is carry out some research and look at the average

  • salary range for your SQL position for your job, and then you know, give them that range.

  • I’ve given $40,000 to $48,000 there. I've met them halfway, basically, so that I'll

  • be comfortable with that. I think that's a great answer because it's a win-win. Question

  • 21: In SQL, what is a subquery? “A subquery

  • is often referred to as an inner query or inner select. As the name suggests, it is

  • an SQL query nested inside a larger query, such as a SELECT, UPDATE, or INSERT statement,

  • or indeed inside another subquery. A subquery can be used to retrieve data that will be

  • used in the main query. This in turn provides a condition to restrict the retrieval of data

  • even further.” Question 22. What happens to the data rows in the table when the table

  • contains a clustered index? What happens to the data rows in the table when the table

  • contains a clustered index? “The data rows will be stored in order. Cluster indexes sort

  • data rows based on their key values. When a table doesn’t use clustered index, this

  • is called a heapin other words, the data rows will be unordered.” Question 23: So

  • that's the end of your SQL interview. Do you have any questions for the panel? We need

  • to be very careful what we say at the end. What questions are you going to ask? Here

  • is my answer. “Thank you, I would like to ask just two questions: Q1. What are the future

  • plans for the company and how could I help you to achieve your objectives? Q2. If I am

  • successful, what’s the first thing you would want me to concentrate on in this SQL position?”

  • So, we've covered 23 questions! If you would like to download all of those in SLIDE FORMAT,

  • there is a link that has appeared in the top-right hand corner of the screen where you can download

  • these. It will go to my website PassMyInterview.com. Don't forget to tell me the name of your interview

  • in the comments section below. I'll be more than happy to create a video for you with

  • my suggested questions and high scoring answers. Don't forget to connect with me on LinkedIn.com

  • in the description below. Please do SUBSCRIBE. I very much appreciate the support. I hope

  • you've enjoyed that tutorial! And good luck in your pursuit for passing your SQL interview.

  • I hope you have a brilliant day. Thank you.

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

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TOP 23個SQL面試問題及答案!(SQL面試技巧+如何通過SQL面試!)(SQL面試技巧+如何通過SQL面試!) (TOP 23 SQL INTERVIEW QUESTIONS & ANSWERS! (SQL Interview Tips + How to PASS an SQL interview!))

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    林宜悉 發佈於 2021 年 01 月 14 日