SQL & PL/SQL :: How To Validate Given String For Alphanumeric Character

To built the Pl/SQL function or SQL query to validate the given string for alphanumeric character.

I would pass the string of size 10 character, we need to validate first 5 character as alphabet, next 4 character as numeric and last 1 character as alphabet.

I will pass the each row value to the function, it need to return "T" or "F" based on the condition,first 5 character as alphabet, next 4 character as numeric and last 1 character as alphabet.

Here is the DML and DDL.

[code]

create table abc ( classid varchar(10));

insert into abc values ("abcde1234f");
insert into abc values ("abcde12345");
insert into abc values ("ab1de1234f");
insert into abc values ("abcde1234f");
insert into abc values ("abcd21234f");

[code]

Output:

Input : abcde1234f Output : T
Input : abcde12345 Output : F
Input : ab1de1234f Output : F
Input : abcde1234f Output : T
Input : abcd21234f Output : F