SQL FAQs

The SQL acronym stands for Structured Query Language. SQL is used to interact with relational databases. With SQL statements we can retrieve and manipulate data in a relational database or define database objects. For example, the SQL SELECT statement is the foundational command for reading data, i.e., returning a set of records.

SQL is the standard language to interface with RDBMS. Therefore, SQL knowledge is a foundational skill for data professionals ranging from software developers, data engineers, data scientists to BI engineers and data analysts. Relational databases are widely spread across the business landscape. As a result, SQL knowledge is part of the core stack for any practitioner. Mastering SQL enables you to create and extract data efficiently as well as manage a RDMBS. SQL knowledge is critical for building a successful career in any data-intensive field.

After being officially accepted in the late seventies and early eighties, the American National Standards Institute (ANSI) via their Technical Database Committee developed and published the first official SQL standard, ANSI X3.135-1986. Over the years, nine more standards followed, accounting for the dynamic developments in the data world. The most recent SQL standard is SQL2023, identical between ANSI and ISO/IEC. It is important to note that while the standard sets the core functionality and grammar of SQL, each vendor (e.g., Microsoft) adds their own variations and extensions to the language.

A great way to begin your SQL learning journey is to head over to the SQL Quick Reference Guide. This comprehensive document provides an overview of the core functionalities of the SQL languages with lots of linked documents inside offering explanations, walkthroughs, and scenario-based articles. The quick reference guide is beginner friendly. Additionally, MSSQLTips.com offers a webinar series SQL in 30 geared toward new and seasoned data professionals. Some of the most recent sessions include SELECT Basics, SELECT Basics II, INSERT Basics, and UPDATE Basics.

The readers eager to get hands-on can follow this guide to installing SSMS 22, the core software for interacting with SQL Server and hosted databases. Then, the guide to installing the AdventureWorks database for SQL Server 2025 can help you install Microsoft’s sample database. Having SSMS and a sample database in place, you can apply everything you have learned from the quick reference guide, the SQL in 30 series, or elsewhere online.

Programming languages can be classified in two broad categories: procedural and declarative. Procedural languages require the programmer to specify how tasks should be accomplished by defining explicit sequences of operations. On the other hand, declarative languages focus on what needs to be achieved, leaving the underlying system to determine the best execution steps. SQL is a declarative language, which data professionals use to describe what data needs to be retrieved or created, then leaving the execution logic to the SQL engine (e.g., SQL Server.)

The SQL language is based on the fundamentals of set theory and relational algebra. A set is a collection of things, where the individual elements do not matter as much as the whole. Similarly, SQL programmers benefit from thinking about the whole (a table/relation, a relationship between tables, a dataset) rather than thinking about the individual rows or values. SQL works best with whole tables, not individual rows.

A SQL statement is an atomic unit of work that forms a transaction. Any transaction can either completely succeed or completely fail, adhering to the Atomicity, Consistency, Isolation, and Durability (ACID) properties. A SQL statement is a set of instructions that can consist of identifiers, parameters, variables, names, data types, and SQL reserved words that must compile successfully. A brief explanation of transactions and their relation to SQL statement is available here.

The official birth year of SQL is 1973. The original inventors of SQL are Donald D. Chamberlin and Raymond F. Boyce – computer scientists, part of IBM Research at that time. The first commercially released version of SQL came in 1979 by Oracle then called Relational Software.

A Relational Database Management System (RDBMS) is a database system that stores data in objects called tables. The system lets you query and manage that data using SQL. To imagine an RDBMS, the first step is to think about the information that needs to be stored as a group of entities. An entity is something that will be stored in the database. It might be an order, a customer, or an item for sale. Entities have attributes, i.e., certain properties that describe the entity. Entities can have relationships among themselves, i.e., they are connected to each other by means of a key. To read more about the relational database model click here.

Popular RDBMS that use SQL include Microsoft SQL Server, MySQL, PostgreSQL, MariaDB, and Oracle.

Dr. Edgar F. Codd first formulated the relational database model in 1970, while at IBM Research. The idea is that the relation is taken as a “discipline” to guarantee the “accuracy, consistency, and integrity of the data[…]”[1] Over the years different vendors have used this universal foundation to deliver enterprise-grade proprietary implementations. All these implementations (e.g., SQL Server, PostgreSQL, MySQL) have one point in common: they are all RDBM Systems. One of the core benefits of RDBMS is the possibility to change the underlying data of any application without having to change the application. Further insight into the relational model, and alternative approaches to database management are available here.

[1] E. F. Codd, The Relational Model for Database Management, version 2, 1990, Addison-Wesley Publishing Company,  pages 5 and 6.

Other types of DB systems do exist and are referred to as NoSQL databases. These databases host non-relational, semi-structured or unstructured data. This document outlines some of the differences between SQL and NoSQL systems.