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6 articles tagged #SQL.
P.01A data analyst is not a junior data scientist and not a dashboard builder with no opinions. Here's what the role actually requires, how it differs from data scientist and data engineer, and the screen that finds someone whose analysis changes decisions.
P.02Two requests try to update the same row at the same time. Pessimistic locking stops one of them from starting; optimistic locking lets both run and catches the conflict at the end. Here's how each works, with real SQL, and how to pick.
P.03Soft delete keeps a deleted_at column and hides rows instead of removing them. It sounds like the safe default, but it quietly breaks unique constraints, foreign keys, and query performance if you don't design for it up front. Here's the real tradeoff.
P.04dbt turns SQL SELECT statements into a tested, documented, version-controlled data pipeline. Here's how it works and when you should add it to your data stack.
P.05Running totals, rankings, moving averages, lag and lead comparisons: window functions handle the analytics queries that would otherwise require application-side loops or multiple round-trips. Here's how they work.
P.06EditorPickMaster SQL from basics to advanced — SELECT, JOIN, GROUP BY, ORDER BY, indexes, date functions, and more using SQLite with Python.