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functions

Same dog, different leash – functions in SQL

Let’s start with this somewhat odd looking result. I have an inline function that returns a random number between 0 and 20, and I call that for each row in ALL_OBJECTS and then I extract just those rows for which the generated random number is 10. Seems simple enough….but why do I get results for which the value of the second column is most certainly not 10?

With and without WITH_PLSQL within a WITH SQL statement

OK, let’s be honest right up front. The motivation for this post is solely to be able to roll out a tongue twisting blog post title Smile. But hopefully there’s some value as well in here for you if you’re hitting the error:

ORA-32034: unsupported use of WITH clause

First some background. A cool little enhancement to the WITH clause came along in 12c that allowed PLSQL functions to be defined within the scope of the executing SQL statement. To see the benefit of this, consider the following example that I have a personal affinity with (given my surname).

Let’s say I’ve allowed mixed-case data in a table that holds names.

Determined on Determinism

I’m feeling very determined on this one. Yes I have a lot of determination to inform blog readers about determinism, and yes I have run out of words that sound like DETERMINISTIC. But one of the most common misconceptions I see for PL/SQL functions is that developers treat them as if they were “extending” the existing database kernel. By this I mean that developers often assume that wherever an existing in-built function (for example TO_NUMBER or SUBSTR etc) could be used, then a PL/SQL function of their own creation will work in the exactly the same way.

Often that will be the case, but the most common scenario I see tripping up people is using PL/SQL functions within SQL statements. Consider the following simple example, where a PL/SQL function is utilizing the in-built SYSTIMESTAMP and TO_CHAR functions.