Structured Query Language, or SQL for short, is a powerful database language geared toward structure data. As its name suggests, SQL is adept at querying databases to acquire the data you need, in a useful format. However, it includes commands that involve the creation or alteration of databases so that they can fit the requirements of your data architectural model. SQL is essential for both data scientists and other data professionals. Let's look into it more, along with its various variants.
Although the tasks performed by SQL (when it comes to data wrangling), you can perform with other programming languages too, its efficiency and relative ease of use make it a great tool. Perhaps that's why it's so popular, with many variants of it. The most well-known one, MySQL, specializes in web databases, though it can also be used for other applications. Other variants, such as PostgreSQL, are mostly geared towards the industry. All this may seem somewhat overwhelming, considering that each variant has its peculiarities. However, all of these SQL variations are similar in their structure, and it doesn't take long to get accustomed to each one of them if you already know another SQL variant.
Yet, all of the SQL databases tend to be limited in the structure of the data. In other words, if your data is semi-structured (i.e., there are elements of structure in it but it's not tabular data), you need a different kind of database. Namely, you require a NoSQL (i.e., Not Only SQL) one. Databases like MongoDB, MariaDB, etc. are of this category. Note that NoSQL databases have many commands in common with SQL, but they are geared toward a different organization of column-based data. This characteristic enables them to be faster and able to handle dictionary-like structures.
Naturally, there are plenty more kinds of SQL variants, primarily under the NoSQL paradigm. However, beyond these SQL-like databases, there are also those related to graphs, such as GraphQL. These specialized systems are geared towards storing and querying data in graph format, which is increasingly common nowadays. All these database-related matters are under the umbrella of data modeling, a field geared towards organizing data flows, optimizing the ways this data is stored, and ensuring that all the people involved (the consumers of this data) are on the same page. Although this is not strictly related to the data science field, it's imperative, plus knowing about it, enables better communication between the data architects (aka data modelers) and us.
You can learn more about SQL and other data modeling topics through the Technics Publications website. There, you can use the coupon code DSML for a 20% discount on all the titles you purchase. Note that this code may not apply to all the video material you'll find there, such as the courses offered. However, you can use it to get a discounted price for all the books. I hope you find this useful. Cheers!
Zacharias Voulgaris, PhD
Passionate data scientist with a foxy approach to technology, particularly related to A.I.