During the 7Up workshop, a workshop geared towards experienced developers who want to get up to speed with everything that happened in Oracle since release 7, one of the “tricks” that passes by is how to implement the Business Rule:
This is an answer to Troels Arvin comment to my earlier post comparing different hierarchical methods.
The predicate limiting the size of the Integers relation would fit more naturally to the outer query block:
with integers(num) as (
select 1 num from dual
select num+1 from integers
) select * from integers where num < 10 ;
Pushing predicate inside [...]
There were a couple of inspiring presentations at the latest PDC conference: the technical DSL session, and the introduction to the Oslo Modeling platform. Watch out for an amusing moment closer to the end of the second show (around 45 min), when somebody in the audience asked how this tool is compared to XML. Don [...]
When comparing different hierarchical SQL query methods many people cite inefficiency of tree structure organized into adjacency list. They claim inferior performance of the methods that the big three vendors supplied to handle such structure; in particular, oracle proprietary connect by extension, and DB2 & SQL Server recursive view. I usually dismiss blanket statements like [...]
Limitation on computer integer representation put a limit on the size of a tree that Nested intervals/Matrix method can accommodate. For example it is reasonable to ask if the method would be able to deal with a tree with 200 levels with 2000 children at each node. It is easy to see that it can’t. [...]
This issue is becoming a recurring theme of mine. This time it has been triggered by OTN exchange. To my surprise, people have difficulty accepting this seemingly obvious idea.
In SQL there is syntactic difference between a predicate and a table. However, let’s look beyond what you may have learned from syntax diagrams in Oracle SQL [...]