Add a Tableau SQL engine that allows a data set to be built in 2 (or more) steps.
I know I ask for much, but my intent is not a full-blown SQL engine — although it might be if something like PostgreSQL
is doing the background work — but rather support of basic SQL techniques that allow us in a simple way to
(1) reshape data and or (2) add dimensions from external sources.
Here is a simplified example with an external date dimension in step 2 that is used to reshape data:
Step 1: Custom SQL from Microsoft SQL Server
SELECT Event_ID, Start_Time, End_Time
Step 2: Custom SQL between result set of step 1 and a (small) date dimension in a text file
SELECT d.Date e.Event_ID
FROM [Step 1] e, [Alias of external source]* d
WHERE d.Date BETWEEN Start_Time AND End_Time
* [Alias of external source] can be any external source supported by Tableau. Multiple tables from various sources should be allowed.
See example of above query in attached workbook in The specified item was not found..
- Reshaping Data
- Adding External Dimensions
- Data Masking read more