Preparing Data

http://kb.tableausoftware.com/articles/knowledgebase/preparing-excel-files-analysis
http://kb.tableausoftware.com/articles/knowledgebase/addin-reshaping-data-excel

anonymizing data for Tableau

http://community.tableausoftware.com/thread/118843

DATE() and STR() functions behave differently depending on the data source (Excel/text/Access vs. extract)

http://community.tableausoftware.com/message/179624

Joining Vs. Blending

http://www.tableausoftware.com/support/knowledge-base/join-vs-relationship-60
http://www.tableausoftware.com/support/knowledge-base/summary-and-detail-60

When one data source has subcategory & measures, and another has category & subcategory, can use Primary Groups to effectively create the category within the first data source. KB has article on this, search for “creating primary groups from a secondary source”.

Data blending and getting aggregations right:

Workbook with three options (extract, control data relationships for blend, custom SQL) by Jeff Mills:
http://community.tableausoftware.com/message/183888#183888
http://community.tableausoftware.com/thread/118319

Creating a Tableau Data Source .tds for connecting to just the database and not the table by Craig Bloodworth:
http://www.theinformationlab.co.uk/2012/11/26/connect-to-a-database-without-specifying-a-table-video/

Outer joining multiple Excel tables
https://www.interworks.com/blogs/tmccullough/2013/06/26/outer-joining-multiple-excel-tables-tableau-8

Custom datasource config files:
http://community.tableausoftware.com/message/227764