Category: Blog

This is the third hour of a three hour set of presentations on intermediate T-SQL techniques and features.

This presentation covers the window functions that are available in SQL Server. Some of these functions were introduced in SQL Server 2005 and some in SQL Server 2015. We start with a brief introduction to what a window is, how a partition works, and then look at ordering and framing of rows. Then we cover the following in demonstrations:

ROW_NUMBER()

RANK(), DENSE_RANK(), and NTILE()

The OVER clause and windowing in SQL Server 2012

Using PARTITION BY and ORDER BY in the OVER clause

Default framing with RANGE and how ROWS are different

PERCENTILE() functions

This covers a lot of information in an hour, but I try to use small data sets to explain what is happening with the window functions and how they can improve the performance, as well as simplify the code, for a number of common queries.

Slides: TSQL_Windowing.pptx

Code: TSQL_Windowing_code.zip

This is the second of a series of talks I put together on intermediate T-SQL topics that many database developers might not understand. In this talk, we cover the other join-type operators that exist in the FROM clause, outside of the INNER, OUTER, FULL, and CROSS join clauses. We break this hour into three main areas, covering:

• PIVOT and crosstabs
• UNPIVOT
• APPLY

Most of the time is spent on the APPLY operator, which is arguably the most useful of the three. I show how APPLY is like an inner or outer join, and also how it can be used to improve performance of a scalar function, how it can be used to run some queries that are difficult with INNER JOINs, and how we can use this to easily find query plans and code in performance tuning.

The PIVOT operator is compared to a crosstab, which is similar. We see how to write a query using either method. We also show the UNPIVOT operator.

Slides: TSQL_IntermediateQueries.pptx

Code: TSQLPIVOT_Unpivot_Apply.zip

This session is an intermediate T-SQL session that helps users learn how to write better T-SQL code by covering a few items that many database developers might not be aware of. In an hour, users will lean how to:

• write and use CTEs to simplify complex queries.
• learn basic error handling, including recommendations for SQL Server 2012 and beyond with THROW.
• use templates to store common code elements
• tricks in SSMS to speed up code development
• understand what a tally table is and how to use it to perform a few common tasks.

This is the beginning of a three hour series I have on intermediate T-SQL code.

Slides: TSQL_WritingCleanerCode.pptx

Code: TSQL_CleanerCode.zip