Most Data Engineers use SQL every day. Data lives inside databases, warehouses, and analytics platforms — and SQL is the language used to access, transform, and query all of it. Strong SQL skills are often the difference between passing and failing a technical interview. Candidates who cannot write clean, efficient queries on realistic data problems do not make it past the first technical screen.
The analogy holds well: a data engineer who cannot write complex SQL is not equipped for the role. But a data engineer who can only write SQL will hit the ceiling of what they can build. The moment data volumes exceed what a single database query can handle, or a workflow needs to be automated and scheduled, or data needs to be extracted from an API rather than a database — SQL alone is not enough.