SQL Window Functions Expert

Master SQL window functions for advanced analytical queries including ranking, running aggregates, time-series analysis, and cohort calculations across PostgreSQL, Snowflake, and BigQuery.

Gold

v1.0.00 activationsData & AnalyticsTechnologyadvanced

SupaScore

83.25

Research Quality (15%)

8.5

Prompt Engineering (25%)

8.5

Practical Utility (15%)

8.5

Completeness (10%)

8.5

User Satisfaction (20%)

Decision Usefulness (15%)

Best for

▸Building complex running totals and moving averages for financial reporting dashboards
▸Creating customer cohort analysis with LAG/LEAD functions for retention metrics
▸Implementing ranking systems (ROW_NUMBER, RANK, DENSE_RANK) for top-performing products by region
▸Optimizing slow window function queries causing memory pressure in billion-row data warehouses
▸Converting Excel-based calculations to scalable SQL window patterns for automated reporting

What you'll get

●Complete SQL queries with proper OVER clause syntax, named windows for readability, and CTE patterns for filtering window results
●Performance optimization recommendations including specific index suggestions and frame specification explanations
●Database-specific syntax variations with warnings about dialect differences and implicit frame behavior

Not designed for ↓

×Basic SELECT queries or simple aggregations without partitioning
×Database administration tasks like user management or backup strategies
×Data modeling or schema design decisions
×ETL pipeline orchestration or data ingestion workflows

Expects

Analytical requirements with clear business context, sample data structure, and target database platform (PostgreSQL, Snowflake, BigQuery).

Returns

Optimized SQL queries with proper window specifications, performance considerations, and dialect-specific recommendations with execution plan analysis.

Evidence Policy

Enabled: this skill cites sources and distinguishes evidence from opinion.

sqlwindow-functionsanalytical-queriespostgresqlsnowflakebigqueryrankingrunning-totalslag-leaddata-analyticsquery-optimizationcohort-analysis

Research Foundation: 8 sources (4 official docs, 2 books, 1 industry frameworks, 1 web)

This skill was developed through independent research and synthesis. SupaSkills is not affiliated with or endorsed by any cited author or organisation.

Version History

v1.0.02/16/2026

Initial release

Works well with

BigQuery Analytics ExpertGold Cohort Analysis DesignerGold PostgreSQL Advanced ExpertPlatinum Snowflake Data Modeling ExpertGold SQL Query OptimizerPlatinum

Need more depth?

Specialist skills that go deeper in areas this skill touches.

SQL Performance Tuning ExpertPlatinum Database Indexing StrategistGold Streaming Analytics SpecialistGold

Common Workflows

Advanced Analytics Pipeline

Build complex analytical queries with window functions, design cohort analysis frameworks, then create executive dashboards

sql-window-functions-expert→Cohort Analysis Designer→dashboard-design-strategist

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