SQL
Also written as Structured Query Language
The standard language for querying and managing data in relational databases.
Think of it like
Like a standardized way of asking a librarian for exactly the books you want — 'every mystery novel published after 2010' — instead of searching the shelves yourself.
Junior or senior?
Junior sounds like
Says they 'know SQL' with no further detail.
Senior sounds like
Can walk through the last complex query they wrote and the problem it solved.
Ask them
“Walk me through the last complex SQL query you wrote — what problem was it solving?”
Sounds like real experience
Describes a specific query's actual complexity — a multi-table join, a window function, a query they had to optimize — and the real problem it solved.
Probe further if
Describes SQL only as 'pulling data out of a database' without describing a specific query, join, or performance problem they personally worked through.