Oracle 12c - SQL Loader Invalid month Error - oracle

Question

I'm getting ORA-01843: not a valid month error while loading the data using tab delimited text file with sql loader 11.1.0.6.0 on oracle 12c.
control file:
options (skip=1)
load data
truncate
into table test_table
fields terminated by '\t' TRAILING NULLCOLS
(
type,
rvw_date "case when :rvw_date = 'NULL' then null WHEN REGEXP_LIKE(:rvw_date, '\d{4}/\d{2}/\d{2}') THEN to_date(:rvw_date,'yyyy/mm/dd') else to_date(:rvw_date,'mm-dd-yy') end"
)
Data:
type rvw_date
Phone 2014/01/29
Phone 2014/02/13
Field NULL
Phone 01/26/15
Field 02/25/12
Schema:
create table test_table
(
type varchar2(20),
rvw_date date
)

Answer 1

The SQL*Loader control file is interpreting a backslash as an escape character, it seems. The SQL operator section shows double-quotes being escaped too; it ins't obvious it would apply to anything else, but it kind of makes sense that a single backslash would always be assumed to be escaping something.
Your regular expression pattern needs to double-escape the \d to make the pattern work in the file as it does in plain SQL. At the moment the pattern is not matched, so all the values to go the else, which is the wrng format mask (even when they are both corrected).
This works:
options (skip=1)
load data
truncate
into table test_table
fields terminated by '\t' TRAILING NULLCOLS
(
type,
rvw_date "case when :rvw_date = 'NULL' then null when REGEXP_LIKE(:rvw_date,'\\d{4}/\\d{2}/\\d{2}') then to_date(:rvw_date,'yyyy/mm/dd') else to_date(:rvw_date,'mm/dd/rr') end"
)
With your original data that creates rows:
alter session set nls_date_format = 'YYYY-MM-DD';
select * from test_table;
TYPE RVW_DATE
-------------------- ----------
Phone 2014-01-29
Phone 2014-02-13
Field
Phone 2015-01-26
Field 2012-02-25