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SQL Interview Questions and Answers
Do you want to ace your next SQL interview? Do you need a quick refresher on the fundamentals of SQL programming? We've compiled all the best questions and answers for this blog post. You'll find out how to answer those trickier questions with ease, as well as what may be asked in an interview. This is one of our Gems of Knowledge articles so we hope it's helpful! It has been compiled by two experienced programmers who have interviewed many candidates for SQL positions in the past.
I will be writing multiple articles, videos on this topic so that I cover most of the SQL interview questions and hands-on answers as well. So, if you are not comfortable with a particular topic or concept mentioned in this article then please do watch my video on that and post your questions/
This article is just to give an overview of what will be asked during the SQL interview.
We are also planning to put together a blog post on what will be the ideal answer for each question so that you can prepare yourself accordingly.
Now let's begin with basic questions
Below is an example of this type of interview question: What do you know about SQL? How would your boss describe your knowledge of it? Where would you rate your abilities?
The first question is an icebreaker, and the interviewer wants to get a sense of your familiarity with SQL. The second question gives you the opportunity to brag about your skills a bit! It's important to be realistic in your self-assessment, though - don't oversell yourself. Try to find a middle ground where you can confidently say that you're knowledgeable about SQL and have the ability to solve problems.
The interviewer may also ask more specific questions about your experience with SQL, such as:
- What are some of the most challenging aspects of working with SQL?
- Can you give me an example of a time when you needed to solve a SQL problem without help?
- Can you name some of the ways that programmers interact with SQL databases?
- How would you write an 'Update' query in SQL for updating records/tables in the database?
This list is not exhaustive. The interviewer may also ask about more specific concepts (e.g., foreign keys, table relationships)
"Most challenging aspects of working with SQL?"
The most challenging aspect I would say is to understand the flow and write efficient code. In some cases it becomes difficult for a novice programmer to get the idea on how this works so he/she has to take help from seniors who have been experienced in this field.
"Can you give me an example of a time when you needed to solve a SQL problem without help?"
Yes , I have worked on many projects where there were no seniors around, so it was bit challenging for me initially but eventually with my experience and expertise in this field I could handle that well . You need to be proactive and learn as much as you can while working on such projects.
"Can you name some of the ways that programmers interact with SQL databases?"
There are multiple ways a programmer interacts with an SQL database. Some common methods are using programmatic statements, stored procedures, triggers, or user-defined functions. Additionally, many developers also rely on graphical front-ends such as MySQL Workbench and SQL Server Management Studio.
Here are some of the common and very basic questions. As I said before, I will be creating multiple articles and videos to cover the most basic to advance levels.
Question: What is the difference between a primary key and a unique key?
A primary key is a column or set of columns in a table that uniquely identifies each row. A unique key is similar to a primary key, but it can be composed of more than one column. In other words, if you have two columns in your table that are NOT part of a composite primary key, then they cannot have the same value for any given row
Question: What is an index in SQL?
An index contains a list of all values from one or more columns in your table and their corresponding locations within that table. The indexes should be created on fields which you anticipate will be frequently searched or sorted on.
Question: What is a foreign key in SQL?
A foreign key is a link between two tables where the data matches across those two tables, for example, when you have an Orders table and an Order Details table that refer to each other's rows. In this case, there will either need to be a foreign key in the Order Details table that relates back to the Orders table and/or vice versa.
More to come in upcoming articles and videos. If you haven't subscribed to my channel yet, please go ahead do so.
Rohan Suresh
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