SQL Skills You Need for Data Scientist Jobs

Data scientists are tested on SQL nearly as hard as on Python — because in real jobs, the data comes from a database before it reaches a notebook. This is the bar to aim for.

Key Points

• Complex multi-table joins and CTE-structured queries
• Window functions as second nature (interviews love top-N-per-group)
• Feature extraction in SQL: per-entity aggregates, recency/frequency metrics
• Enough optimisation sense to not melt the shared warehouse
• Fluency moving between SQL and pandas (read_sql, to_sql)
• Understanding sampling and point-in-time correctness for training data