SQL developer interview questions and tests

Companies typically deal with a huge amount of data stored in databases. As most businesses seek to do even more with their data ion the future, they need SQL specialists who can analyze and access data. That said, you need to be sure that the person you entrust your data with is reliable and has the right skills. In other words, your data is safe only in the hands of a qualified SQL specialist.

SQL developer interview questions and tests verify the level of expertise of the Structured Query Language and some basic concepts of relational databases.

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Technologies covered:

Programming language: SQL

SQL frameworks and libraries: MySQL, PostgreSQL, Oracle, MSSQL and others

Java
JUNIOR
Tested skills
Duration
120 minutes max.
Evaluation
Automatic
Test overview

Front End programming task - Level: Easy

JavaScript | TypeScript | Invoice application - frontend - Implement the front-end part for merging and aggregating the invoice data with currency exchange rates.

Back End programming task - Level: Easy

Java | Invoice application - backend - Implement the backend part for searching and aggregating invoice data with the service and the DAO methods.

Data Science
JUNIOR
Tested skills
Duration
45 minutes max.
Evaluation
Automatic
Test overview

Task - Level: Easy

SQL | Stamps catalogue | The three highest prices - Select three stamps (price and name) with the highest price.

Programming task - Level: Easy

Python | Pandas | HTML table parser - Implement a function to convert HTML table into a CSV-format file.

Python
MIDDLE
Tested skills
Duration
120 minutes max.
Evaluation
Automatic
Test overview

Choice questions

assessing knowledge of Python

Programming task - Level: Medium

Python | Vehicle sales report - Implement an application to create reports based on the vehicle sales data warehouse.

DevOps
SENIOR
Tested skills
Duration
66 minutes max.
Evaluation
Automatic
Test overview

Choice questions

assessing knowledge of DevOps, Docker

DevOps task - Level: Hard

DevOps | Master of Disaster Recovery (CentOS) - Recover data from broken MariaDB/MySQL database.

DevOps
SENIOR
Tested skills
Duration
66 minutes max.
Evaluation
Automatic
Test overview

Choice questions

assessing knowledge of DevOps, Docker

DevOps task - Level: Hard

DevOps | Master of Disaster Recovery (Ubuntu) - Recover data from broken MariaDB/MySQL database.

PostgreSQL
MIDDLE
Tested skills
Duration
44 minutes max.
Evaluation
Automatic
Test overview

Choice questions

assessing knowledge of SQL

Code gaps

assessing knowledge of SQL

Task - Level: Medium

SQL | PostgreSQL | Hotels - hotels page optimization - Improve the performance of the the hotels listing page which currently uses ORM.

MongoDB
MIDDLE
Tested skills
Duration
51 minutes max.
Evaluation
Automatic
Test overview

Choice questions

assessing knowledge of SQL, MongoDB, NoSQL

Code gaps

assessing knowledge of MongoDB

Task - Level: Medium

SQL | Customer Data - Find all the customers whose first and last names are not unique in this database, as well as the number of times each first and last name pair appears in the database.

PHP
MIDDLE
Tested skills
Duration
60 minutes max.
Evaluation
Automatic
Test overview

Code gaps

assessing knowledge of SQL

Choice questions

assessing knowledge of ES6, JavaScript, CSS, HTML, WCAG 2.0, Web Accessibility

Programming task - Level: Medium

PHP | Categories Repository - Implement PDO queries that will return valid results about movies to users.

PHP
SENIOR
Tested skills
Duration
88 minutes max.
Evaluation
Automatic
Test overview

Choice questions

assessing knowledge of SQL, ES6, JavaScript, AJAX, Web development

Programming task - Level: Hard

PHP | XML-CSV Converter - Implement filtering and data transformation methods to pass all the tests.

PHP
JUNIOR
Tested skills
Duration
41 minutes max.
Evaluation
Automatic
Test overview

Code gaps

assessing knowledge of SQL, CSS, HTML

Choice questions

assessing knowledge of JavaScript

Programming task - Level: Easy

PHP | Faker | Basic data manipulation - Implement all the methods in the app/Faker class.

MongoDB
SENIOR
Tested skills
Duration
56 minutes max.
Evaluation
Automatic
Test overview

Choice questions

assessing knowledge of SQL, MongoDB, NoSQL

Code gaps

assessing knowledge of MongoDB

Task - Level: Hard

SQL | Fill sparse table - Write a query that will return the list of all users with the creation date and return the date from the previous not-null row for the entries affected with the bug.

MongoDB
JUNIOR
Tested skills
Duration
27 minutes max.
Evaluation
Automatic
Test overview

Choice questions

assessing knowledge of SQL, MongoDB, NoSQL

Code gaps

assessing knowledge of MongoDB, SQL

Task - Level: Easy

SQL | Stamps catalogue | CASE statement - Make a select statement, by which you will divide your stamps collection into 3 groups.