JMeter: while controller not terminating upon zero count - while-loop

Question

This is a continuation of my question JMeter: How to benchmark data deletion from database table in batches?. I adopted the solution proposed by Dimitri T, and now I am using the test case for Oracle DB.
My test case starts by inserting 1000 entries, using 100 threads in 10 loops. After that, it deletes where rownum < 250.
However, my test case is no longer able to detect that the table is empty. When I view the response data in my result tree, I see the following:
249 updates
249 updates
249 updates
249 updates
4 updates
0 updates
0 updates
0 updates
...
JMeter itself does not report any errors occurring.
My thread group looks like this:
...(separate thread group to do INSERT)...
Thread Group: Do DELETE
Txn Ctrl: DELETE
While Loop: tbl still has data
JDBC Request: DELETE from tbl
JDBC PostProcessor
Loop condition is defined as follows:
${__jexl3('${count_1} > 0',)}
(As a slight change from the solution in my previous question, I surrounded the condition in quotes to prevent the ambiguous expression error from showing up.)
JDBC request is defined as follows:
delete from tbl where (entrydt < ${endDt}) and (rownum < ${deleteLimit})
(User-defined variables endDt and deleteLimit have values TO_DATE('2019/02/01 00:00:00', 'yyyy/mm/dd hh24:mi:ss') and 250 respectively.)
JDBC post-procesor is defined as follows:
[Select statement] select count(*) from tbl
Variable names: count (All other fields are empty.)
Handle ResultSet: Store as String
I have tried
Changing the loop condition; the quotes do not matter; neither do changing ${count_1} to ${count}
Changing the post-processor; between variable names, result variable name, and how the result set is handled

Answer 1

who told you to surround the expression with quotation marks? First you break the working solution and then you're complaining that the expression provided doesn't work.
Just define count_1 as as positive number via User Defined Variables and you will not have any errors in jmeter.log
If for some reason you're not willing to do this or cannot do this - you can consider migrating to __groovy() function with an extra check of count_1 variable being set like:
${__groovy(vars.get('count_1') == null || (vars.get('count_1') as int) > 0,)}