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apex_application.g_f0x array processing in Oracle 12

If you created your own "updatable reports" or your custom version of tabular forms in Oracle Application Express, you'll end up with a query that looks similar to this one:
then you disable the "Escape special characters" property and the result is an updatable multirecord form.
That was easy, right? But now we need to process the changes in the Ename column when the form is submitted, but only if the checkbox is checked. All the columns are submitted as separated arrays, named apex_application.g_f0x - where the "x" is the value of the "p_idx" parameter you specified in the apex_item calls. So we have apex_application.g_f01, g_f02 and g_f03.
But then you discover APEX has the oddity that the "checkbox" array only contains values for the checked rows. Thus if you just check "Jones", the length of g_f02 is 1 and it contains only the empno of Jones - while the other two arrays will contain all (14) rows.
So for processing you need to work through g_f02 and find the corresponding index in the g_f01 array. And then you need to use that index to find the corresponding value in the g_f03 array. Check the code example below...
To me this looks quite complex - even for a simple example as this one. But hey, that's the way it is. Everybody is doing it this way, so it must be ok.

Until Oracle Database 12.1 came along .... and you have read this:
What is explained in that post, can also be applied to apex_application.g_f0x arrays! So knowing that, we can rewrite the code above using a way more elegant cursor :
Just use that cursor in your loop to process the changes. Although you still have to figure out the join between the different arrays, it is now all done within one SQL statement. Simple, elegant, effective. And probably faster too if you have a larger result set.

BTW, as you can read here, you can't use this PL/SQL table() construct inside a DML statement. So you can't use it directly in an insert, update, delete or merge command as that will result in an "ORA-00902 - Invalid datatype" error. It would be really, really nice if that limitation is lifted in a future version!


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