convert to iso8601 format

[Vijay77]

I have a following date i have to convert it to numeric and iso8601 format

UN-UNK-1975

UN-OCT-1986

18-OCT

Expected o/p:

1975

10-1986

.

Thanks

[SASKiwi]

1975 and 10-1986 are not valid dates in any format - a date requires a day, month and a year. If you only know the year 1975 what would you default your date to? 01-01-1975? Similarly does 10-1986 become 01-10-1986?

[Shmuel]

You need more examples in order to define the algorithm.

I suggest to locate in your input:

1) A 4 digits sub-string  assumed as a year

2) A 3 characters sub-string to be checked against a list or by a format

    containing all months (JAN FEB MAR ...)

3) Is there in your input full name month? (JANUARY FEBRUARY ...) or

    mixed case like January February ... ? or month given in digits ?

    If answer is positive you need more code in the algorithm.

[Kurt_Bremser]

Your expected output does not conform to ISO 8601. Your question makes no sense.