Windowing Functions in SQL Server
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This document discusses windowing functions in SQL Server. It provides an introduction to windowing functions and the types: ranking functions, aggregate functions, and analytic functions. It then summarizes improvements in SQL Server 2012, including new analytic functions, enhancements to aggregate functions, and new keywords for defining partitions. The document ends with a question and answer section.
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Windowing Functions in SQL Server
- 1. Dinesh Karunarathna B.Sc. (Eng.),MCTS – SQL Server Senior DBA – Pearson Lanka [email protected] http://www.dbbitsandpieces.blogspot.com/
- 2. Introduction What are the windowing functions Functions that operates/ manipulates on set of rows Types of windowing functions Ranking functions - Returns a ranking value for each row Aggregate functions - Performs calculations on set of values Analytic functions - Compute moving averages, running totals, percentages… Improvements of windowing functions in SQL Server 2012
- 3. New functionality in SQL Server 2005 OVER() Clause – Used to define a window or user specified set of rows within a query result set PARTITION BY Clause - Divides the query result set into partitions Ranking functions Changes in aggregate functions
- 4. Partitioning a data set Partitioned by LocationID Partitioned by CustomerID
- 5. Ranking functions ROW_NUMBER() - Sequential number of a row within a partition of a result set RANK() - Rank of each row within the partition DENSE_RANK() - rank of rows within the partition of a result set, without any gaps in the ranking NTILE() - Distributes the rows in an ordered partition into a specified number of groups
- 6. Demo…
- 8. Aggregate functions cont… Enhancements in SQL Serve 2005 SUM(Column1) OVER (PARTITION BY Column2) Enhancements in SQL Server 2012 SUM(Column1) OVER (PARTITION BY Column2 ORDER BY Column3)
- 9. Demo…
- 10. New features with SQL Server 2012 Analytic functions FIRST_VALUE() LAST_VALUE() LEAD() LAG() PERCENT_RANK() PERCENTILE_COUNT() PERCENTILE_DISC() CUME_DIST()
- 11. New features with SQL Server 2012 cont … Enhancements of Aggregate functions ODER BY with OVER() clause Enhancements of defining the partition (window) ROWS/RANGE CURRENT ROW PRECEDING FOLLOWING UNBOUNDED
- 12. Demo …
- 13. Q & A Which function can be best used to retrieve daily increment? List five new key words used to define a window of a dataset
- 14. Thank you.