Structured Query Language, or SQL, is a language used in programming to manipulate data by inserting, storing, or retrieving, updating, and searching databases.
A Relational Database Management System (RDBMS) is a system that appears as a table containing data that can be compared to other data within the system.
What You Need to Know
Degrees in relevant fields are important, however, they should not be the basis for hiring developers. Recruiters need to look at their prior experience in real applications.
One thing developers must know is indexing and how to use it appropriately. Indexing allows data to be located quickly using keys from the SQL server. This skill can resolve most problems and should be a requirement when hiring developers.
- Database Administrator
- Business Analyst
- Software Developer
- Net Developer
- Quality Analyst
- SQL Server Developer
Why Learn SQL?
An Indeed analysis by Josh Devlin reported that SQL skills are required for 42.7% of jobs posted on the site. Other postings with ‘data’ in the title may require SQL skills. Due to its array of uses, social media corporations have benefited from using it because of the amount of data collected on a daily basis. Facebook and Twitter are among the top social media users. Whether you work in a relevant field or know nothing about programming, you can still learn SQL. There is basic terminology, but the applications of this skill are limitless.
These developers should be able to use databases appropriately and effectively in a variety of formats.
SQL developers must be able to index within a database to locate the correct information. This particular skill accelerates the searching process and saves time.
Filtering narrows down the data that is searched, making it easier to index databases. One common command is ‘WHERE’. This allows a developer to filter a database down to a location and is often used for searching records. Another command, ‘JOIN’, is self-explanatory—it combines data according to how the JOIN command is specified (i.e. JOIN: INNER, JOIN: RIGHT OUTER, etc).
Referred to as a subquery, inner query, or nested query, this skill allows SQL developers to take specified data from multiple tables and combine them. It is similar to the JOIN command.
Used with queries, these plans explain how a query functions. They can also show whether indexes are working properly and assist developers with finding, fixing, and understanding problems in the query system.
Backing Up Data
Knowing the difference between types of data backups and utilizing them effectively can prevent data loss. Depending on the data collected, the type of backup that will need to be used may vary. Some types include: full backups, file backups, partial backups, and transaction log backups.
SQL developers should know how to improve their servers’ performance, so it runs quickly. When servers run poorly, the quality of data, they collect decreases.
Questions to Ask
- How long ago have you worked with [relevant company].
If a developer hasn’t used their skills in a few years, their practical skills may be outdated. SQL developers must be able to adapt to current practices.
- How often and to what degree did you use your SQL skills? What position or involvement did you hold in the projects you worked on?
The candidates’ answer can help gauge their experience levels, influence, and ability to make logical choices if needed.
- How big were the databases you worked with?
Candidates with less experience will most likely work on smaller databases. Seasoned developers may have worked with data on a larger scale.
- How might you explain SQL and NoSQL to someone in layman’s terms?
Candidates should understand the differences between both languages and be able to break them down to a simple level. How well they answer this question can show the depth of their knowledge as a developer. Some differences are:
– SQL is table-based, NoSQL is document-based
– SQL has a vertical appearance, NoSQL is horizontal
– NoSQL is better for simple systems, SQL is good for complex systems
Pre-Hire Skill Assessments
Benefits of having candidates fill out SQL assessments include:
– Eliminating unqualified candidates
– Allows quality time with top applicants
– Tests knowledge of important skills
– Improves data for future hiring processes