Member-only story
If you’re applying for a job in the field of data science, data engineering, or business analytics, there’s a good chance that you’ll have to work with SQL at one point or another. Knowing how to manage and query your own data is incredibly important in these fields. If you’re new to SQL, or need to brush off a rusty set of skills to address the current marketplace, it can be difficult to figure out what you need to know about SQL in order to be competitive in your field.
That being said, here are the basics:
Invented in 1974, SQL is a programming language designed to interface with Relational Database Management Systems (RDBMS). An RDBMS structures data into tables made up of rows (called “records”) and columns (called “fields”), which can then be queried, combined, and manipulated in various ways to achieve a desired outcome.
MySQL, Microsoft SQL Server, Oracle, Amazon Redshift, and IBM DB2 are all examples of RDBMS-based software. The chances that you will encounter one (or more) of these technologies in the course of your career or interview is pretty high. So, let’s make sure you’re prepared.
Subsets of SQL
There are three different subsets of SQL:
- Data Definition Language (or DDL), which allows you to CREATE, ALTER, or DROP tables entirely
- Data Manipulation Language (or DML), which allows you to SELECT or UPDATE existing data, or INSERT new data into an existing table
