APEX

I tried to add multi-row delete (MRD) on a tabular form in one region, couldn't get it working (the region is a file upload/download app that I did by following the how-to document -- which worked well when I followed it to a "T", but as soon as I try to change anything... havoc ensues). Somewhere in the process of struggling with this, another region of the form became hosed. This region has a tabular form with multi-row insert, update, delete, and was working. Now I get a checksum error. I just noticed in a how-to document that it says not to change the select list of a SQL query for a tabular form after it's been generated (which is usually impossible). But I haven't changed the select list in the SQL statement (I might have several days ago -- but it was working after that if I had). Is there any way to get rid of this checksum error or do I have to start over:

Error in mru internal routine: ORA-20001: Error in MRU: row= 1, ORA-20001: ORA-20001: Current version of data in database has changed since user initiated update process. current checksum = "C2FF37C408C0FFD5F929C6207A0A21D2", item checksum = "0BE891017DF96E59364669477F6DB888"., update "SAM"."SW_REQUEST_TARGET" set "REQUEST_TARGET_ID" = :b1, "REQUEST_ID" = :b2, "TARGET_TYPE" = :b3, "TARGET_IDENTIFIER" = :b4, "QTY_ALLOCATED" = :b5, "COMMENTS" = :b6

This is the SQL query for the tabular form:

select
t.request_target_id "REQUEST_TARGET_ID",
t.request_id "REQUEST_ID",
t.target_type "TARGET_TYPE",
t.target_identifier "TARGET_IDENTIFIER",
e.fname||' '||e.lname "EMPNAME",
t.qty_allocated "QTY_ALLOCATED",
t.comments "COMMENTS"
from
"#OWNER#"."SW_REQUEST_TARGET" t,
"#OWNER#"."EMPLOYEE" e
where
t.target_identifier = to_char(e.empno(+))
and "REQUEST_ID" = :P3_REQUEST_ID

It seems for every step forward I make, I go 2 steps backward. I've spent several all-nighters at work (I'm on a deadline to get this done) because I keep running into problems that take forever to solve. I read through the user guide, query the forum, look for solutions in how-to docs, trial and error, compare to other apps, etc., and still cannot find solutions sometimes. For the time I have put into this I could have learned Java and JDeveloper, but now that I'm this far into it, I have to finish it, but I feel like I'll be a blubbering idiot by the time I'm done. Just wanted to share that. I like many things about it, but it's not something that can be mastered easily, there's so much going on behind the scenes that you can't control, or it's very difficult to find the magic sequence of things that gets it to do what you want it to.