Asking for bind variable where none is needed

Question

Good Morning,
I am still working these regexp date_time project.
I have a problem where oracle is asking for a bind variable where it doesn't need any as far as I can see. I am trying to capture various date times in a column and formatting them into one default format used by oracle. Here is what I got which works before I wrap it in the TO_DATE function
There are many when then's but I am using only one here.
select case
when regexp_substr(date_time,'^(0?[1-9]|1[0-2])/(0?[1-9]|[1-2][0-9]|3[0-1])/9[[:digit:]]{4}') is not null
then regexp_substr(date_time,'^(0?[1-9]|1[0-2])/(0?[1-9]|[1-2][0-9]|3[0-1])/9[[:digit:]]{4}')
else date_time
end as new_time
from raw_data;
The above statement works
Now when I want to format the date that I found with this:
select case
when regexp_substr(date_time,'^(0?[1-9]|1[0-2])/(0?[1-9]|[1-2][0-9]|3[0-1])/9[[:digit:]]{4}') is not null
then TO_DATE('regexp_substr(date_time,'^(0?[1-9]|1[0-2])/(0?[1-9]|[1-2][0-9]|3[0-1])/9[[:digit:]]{4}')','MM/DD/YYYY')
else date_time
end as new_time
from raw_data;
I get a request to insert a value for the digit as a bind variable. The digit should be populated from the when statement when it returns not null when a date is found.
Could some one please tell me even if what I wrote here is even possible or make a suggestion to the syntax to get around this issue?
All this is going to be incorporated into an update statement later on.
I am running this on sql developer, oracle 11g.
Thanks for your help in this matter in advance.
regards,
Al

Answer 1

From looking at the code, as you have not supplied any scripts to create a table and demonstrate the error...
Your case statement is trying to return two types
select case
when regexp_substr(date_time,'^(0?[1-9]|1[0-2])/(0?[1-9]|[1-2][0-9]|3[0-1])/9[[:digit:]]{4}') is not null
then TO_DATE('regexp_substr(date_time,'^(0?[1-9]|1[0-2])/(0?[1-9]|[1-2][0-9]|3[0-1])/9[[:digit:]]{4}')','MM/DD/YYYY')
else date_time
end as new_time
from raw_data;or simply
select case when <expr>
            then <RETURN A DATE>
            else <RETURN A VARCHAR2>
        end as new_time
  from raw_data;The column cannot be both.
Sorry I don't know your requirements.
You could drop the else part and just return the converted date.
You could fetch it back in two columns, the ones you can convert in one column (Which would be an oracle date type),
the ones you cannot convert in another (which would be varchar2).
Cheers,
GP>