SQL Spackle #1 Jeff Moden 19 May 2011

About Your Speaker Mostly Self Trained Started with SQL Server in 1995 More than 25,000 posts on SQLServerCentral.com (some are actually useful) 22 Articles on SQLServerCentral.com – Moden/80567/ SQL Server MVP since 2008 Coined the phrase “RBAR” 2 Sessions at PASS 2010 SQL Server Saturday #60 – Brunswick, OH

Agenda Introduction to “Pseudo Cursors” –What they are –Declarative Code –Procedural Code –Examples The Calendar Table –What it is –How to build it –Usage examples

Introduction To “Pseudo Cursors”

Behind the Scenes… What IS SQL Server Really? –It’s nothing more than a very sophisticated file system. What IS a SELECT? –It’s nothing more than “declarative” code that loops through a part of a file identified as a “table”. –It does almost like the code you’d write… find a row, read a row, process a row, loop until done. –It LOOPs in the background so you don’t have to write loops like a front-end Developer.

“Declarative” Code You tell it what you want done SQL Server figures out how to do it. “Set Based” code is where you allow or even help SQL Server do the best job that it can do. It works with more than one row at a time or in “sets” of rows.

“Procedural” Code Easy name to remember because you tell SQL Server how to “proceed” every step of the way. Consists of explicit Loops Consists of “hidden” RBAR such as recursive CTE’s and recursive functions. Is usually quite slow because SQL Server can’t do what it’s supposed to

“Pseudo Cursor” Examples

The “Calendar” Table

What A Calendar Table Is A “Helper” Table Auxiliary Table of Dates A special kind of “Pseudo Cursor” Pre-populated with date related info Use to replace Cursors, While loops, and other complicated code.

Building the “Calendar” Table

“Calendar” Table Code Examples

Grouping “Islands of Dates”