What Is SQL?

SQL is a programming language used to create, manage, and query data held in relational databases, forming the standard way most business applications read and write structured data.

SQL remains the dominant language for working with relational data, which means SQL proficiency is foundational to a huge share of enterprise software, from custom applications through to reporting and analytics tools built on top of the same underlying databases. Poorly written SQL is also a common, avoidable source of performance problems, a slow query can quietly degrade an entire application's responsiveness long before anyone identifies the actual cause.

We write and optimize SQL as a core part of both application development and data engineering work, paying particular attention to query performance as data volumes grow, since a query that performs acceptably on a small dataset can become a serious bottleneck once real world usage scales up. This includes reviewing and tuning existing SQL during modernization projects, where legacy systems often carry years of accumulated, unoptimized queries that were never revisited once they technically worked.