Hiring guide for Declarative SQL(DeSQL) Engineers

Declarative SQL(DeSQL) Developer Hiring Guide

Declarative SQL (DeSQL) is a computer programming language that emphasizes the description of what the program should accomplish, rather than how to accomplish it. It is a subset of the widely-used Structured Query Language (SQL), which was developed by Donald D. Chamberlin and Raymond F. Boyce at IBM in the 1970s. DeSQL is particularly suited for database management systems, allowing users to specify the data needed without detailing how to retrieve it. Its declarative nature simplifies programming tasks, making it a popular choice for managing relational databases. The development and implementation of DeSQL have significantly contributed to the evolution of database technology.

Ask the right questions secure the right Declarative SQL(DeSQL) talent among an increasingly shrinking pool of talent.

First 20 minutes

General Declarative SQL(DeSQL) app knowledge and experience

The first 20 minutes of the interview should seek to understand the candidate's general background in Declarative SQL(DeSQL) application development, including their experience with various programming languages, databases, and their approach to designing scalable and maintainable systems.

What are the basic commands in SQL?
The basic commands in SQL are SELECT, INSERT, UPDATE, DELETE, CREATE, DROP, ALTER, TRUNCATE.
How would you retrieve all records from a table?
You can retrieve all records from a table using the SELECT statement. For example, 'SELECT * FROM table_name;' would retrieve all records from the table.
What is the purpose of the WHERE clause in SQL?
The WHERE clause in SQL is used to filter records that fulfill a specified condition.
Describe the difference between SQL and NoSQL databases.
SQL databases are relational, table-based databases whereas NoSQL databases are non-relational and can be document-based, key-value pairs, graph databases, or wide-column stores. SQL databases use structured query language and have a predefined schema. NoSQL databases have dynamic schemas for unstructured data.
How would you update existing records in a table?
You can update existing records in a table using the UPDATE statement. For example, 'UPDATE table_name SET column1 = value1, column2 = value2 WHERE condition;' would update specific records in the table.
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What you’re looking for early on

Does the candidate have a solid understanding of Declarative SQL?
How well does the candidate understand database concepts?
Can the candidate solve complex queries and problems?
Does the candidate have experience with performance tuning?

Next 20 minutes

Specific Declarative SQL(DeSQL) development questions

The next 20 minutes of the interview should focus on the candidate's expertise with specific backend frameworks, their understanding of RESTful APIs, and their experience in handling data storage and retrieval efficiently.

What is the purpose of the JOIN statement in SQL?
The JOIN statement in SQL is used to combine rows from two or more tables, based on a related column between them.
Describe the difference between INNER JOIN and OUTER JOIN.
An INNER JOIN returns records that have matching values in both tables, while an OUTER JOIN returns all records from one table and the matched records from another table. If there is no match, the result is NULL on the side of the table that does not have a match.
How would you delete records from a table?
You can delete records from a table using the DELETE statement. For example, 'DELETE FROM table_name WHERE condition;' would delete specific records from the table.
What are the different types of SQL commands?
SQL commands are divided into several types, including DDL (Data Definition Language), DML (Data Manipulation Language), DCL (Data Control Language), and TCL (Transaction Control Language).
Describe the difference between DROP, DELETE and TRUNCATE commands.
DROP is used to delete a whole database or just a table.The DELETE command is used to delete specific rows from a table and the TRUNCATE command is used to delete all the rows from a table.
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The ideal back-end app developer

What you’re looking to see on the Declarative SQL(DeSQL) engineer at this point.

At this point, a skilled Declarative SQL(DeSQL) engineer should demonstrate strong problem-solving abilities, proficiency in Declarative SQL(DeSQL) programming language, and knowledge of software development methodologies. Red flags include lack of hands-on experience, inability to articulate complex concepts, or unfamiliarity with standard coding practices.

Digging deeper

Code questions

These will help you see the candidate's real-world development capabilities with Declarative SQL(DeSQL).

What does the following SQL statement do?
SELECT * FROM Employees WHERE EmployeeID = 1;
This SQL statement selects all columns for the employee with an EmployeeID of 1 from the Employees table.
What will be the output of the following SQL statement?
SELECT COUNT(*) FROM Orders WHERE OrderDate >= '2020-01-01';
This SQL statement will return the count of all orders that have an OrderDate on or after January 1, 2020.
What does the following SQL statement do?
SELECT ProductID, SUM(Quantity) FROM OrderDetails GROUP BY ProductID;
This SQL statement calculates the total quantity for each ProductID in the OrderDetails table.
What will be the output of the following SQL statement?
SELECT AVG(Salary) FROM Employees WHERE DepartmentID = 1;
This SQL statement will return the average salary of all employees in the department with a DepartmentID of 1.

Wrap-up questions

Final candidate for Declarative SQL(DeSQL) Developer role questions

The final few questions should evaluate the candidate's teamwork, communication, and problem-solving skills. Additionally, assess their knowledge of microservices architecture, serverless computing, and how they handle Declarative SQL(DeSQL) application deployments. Inquire about their experience in handling system failures and their approach to debugging and troubleshooting.

How would you select unique records from a table?
You can select unique records from a table using the DISTINCT keyword. For example, 'SELECT DISTINCT column1, column2 FROM table_name;' would select unique combinations of column1 and column2 from the table.
What is the purpose of the GROUP BY statement in SQL?
The GROUP BY statement in SQL is used to group rows that have the same values in specified columns into aggregated data.
Describe the difference between HAVING and WHERE clause.
The HAVING clause was added to SQL because the WHERE keyword could not be used with aggregate functions. WHERE is used before grouping and HAVING is used after grouping.

Declarative SQL(DeSQL) application related

Product Perfect's Declarative SQL(DeSQL) development capabilities

Beyond hiring for your Declarative SQL(DeSQL) engineering team, you may be in the market for additional help. Product Perfect provides seasoned expertise in Declarative SQL(DeSQL) projects, and can engage in multiple capacities.