Training on Aggregation Strategies for the SQL Server Queries Certification course. 70-461 See http://stevestedman.com/2015/01/aggregating-data-and-aggregation-strategies/ for more information on aggregation strategies.

1. Presented by Steve Stedman

2. Agenda
 OVER Clause
 PARTITION BY
 With GROUP BY
 Performance

3. OVER
 Introduced in SQL Server 2005
 Aggregation without a GROUP BY
 Also know as “Window Functions” or “Windowing
Functions”.

4. Multiple grouping, with one query?
SELECT Category, SUM(UnitRetail), COUNT(*)
FROM [dbo].[Inventory]
GROUP BY Category;
SELECT UnitRetail, SUM(UnitRetail), COUNT(*)
FROM [dbo].[Inventory]
GROUP BY UnitRetail;

5. Window Functions
SELECT Category,
SUM(UnitRetail) OVER (PARTITION BY Category),
COUNT(*) OVER (PARTITION BY Category),
UnitRetail,
SUM(UnitRetail) OVER(PARTITION BY UnitRetail),
COUNT(*) OVER(PARTITION BY UnitRetail)
FROM [dbo].[Inventory];
.

6. Performance

7. Any Questions?
 OVER Clause
 PARTITION BY
 With GROUP BY
 Performance
 Next Week:
 TOP(N) Queries and Ranking Functions