SQL Window Functions cheat sheet with Shrividya Hegde

Window functions are the thing people look up every single time and still get subtly wrong. This sheet fixes that.

It opens with the syntax anatomy, because once you see that every window function is the same shape, the rest is variation. From there:

• Ranking functions and exactly how each one handles ties
• Aggregate windows: running totals and moving averages
• Offset functions, including the LAST_VALUE trap that bites everyone
• Frame clauses, with a diagram showing the frame sliding row by row
• Copy-ready patterns: dedupe with ROW_NUMBER, top-N per group, gaps-and-islands, month-over-month, cohort tagging
• Named windows via the WINDOW clause, which cuts duplication and reuses one sort
• Dialect notes for Postgres, Snowflake, BigQuery, and MySQL, including QUALIFY

Dialect-specific syntax is flagged where it appears, so you won't paste Postgres casts into BigQuery.