How to find alphabetic characters (a-z, A-Z)

By using '[[:alpha:]]' with regular expressions it is possible to find 
alphabetic characters. By adding {3} at the end we limit the length of matching 
alphabetic characters.


Select * from test_table where REGEXP_LIKE(test_column, '[[:alpha:]]');

Select * from test_table where REGEXP_LIKE(test_column, '[[:alpha:]]{3}');