You are correct, a restart of splunkd is not required when you add lookup tables via the Web UI.
I typically use CamelCase for my variables and always CAPTIALIZE select keywords in the search code (i.e. OR and AS) to match the Splunk doc and make the code easier to follow. OR is required but I don't think AS is; I've used it as 'as'.
The "| inputlookup oracle_returncode.csv" command returns the CSV file header as the field names for each column. Verify that these match your code. The lookup command in your search uses the syntax of
| lookup {LookUp_Tbl_Name} {LookUp_Tbl_Field_1} AS {Event_Field_1} OUTPUT {LookUp_Tbl_Field_2} AS {Event_Field_2}
For more info on the command's format, check out the Lookup Command1 doc. If you create a Lookup Definition (second item on the Settings >> Lookups page), then you do not need to specify the lookup table's CSV file name and use a shorter name instead.
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