Comments on: SSIS Lookup transformation in T-SQL

By: SQL Community time capsule - LobsterPot Blogs

SQL Community time capsule - LobsterPot Blogs — Tue, 11 Aug 2020 03:49:59 +0000

[…] had to think about this one. As much as I like the double OUTER APPLY (SELECT TOP (1)…) thing that I do, especially for protecting my base tables in warehouse loads, I'm not about to […]

By: What were you thinking, Rob? - LobsterPot Blogs

What were you thinking, Rob? - LobsterPot Blogs — Tue, 12 Nov 2019 02:47:39 +0000

[…] grouping by a column that isn’t in the SELECT clause, providing an inverted predicate, doing a double OUTER APPLY (SELECT TOP (1)…), or even providing a table or join hint. I might hope I know what I’m doing, but I also want […]

By: Rob Farley

Rob Farley — Fri, 22 May 2015 04:36:01 +0000

That’s great, Tarek! 🙂

By: Tarek

Tarek — Fri, 22 May 2015 03:42:28 +0000

Hi Rob,
your post helped me a hell lot. I was trying to solve a similar scenario where I wanted to build a parent child table structure and I only knew that the parent is the next of the preceding elements in the list with HierarchyLevel-1. By changing the join that I made first your APPLY statement and constraining my resultset to TOP 1 DESC, I obtained exactly my desired result. Otherwise, by use of a common join I would have gotten as much duplicate rows as much rows of lower level were found in the list before.
Thanks a lot!
Best regards,
Tarek

By: Rob Farley

Rob Farley — Wed, 16 Jul 2014 12:03:34 +0000

Hi Surjit,
The first predicate is on the set d1, which is reflected in the Startup Filter. It means it only does this lookup if the first one (d1) has failed to find something.
The second predicate is on the tables d and f, and is used to find the record in the dimension table.
Does this help?
Rob

By: Surjit

Surjit — Wed, 16 Jul 2014 11:51:48 +0000

Hi,
I had below doubt on second outer apply
When there is condition d1.BusinessKey IS NULL
How can this cindition execute "AND d.BusinessKey = f.DimBK "
Thanks,
Surjit