Question

In my pl/sql script Oracle treats the letter ‘e’ as upper case when searching by the [:upper:] Character Class Syntax.

i.e.

REGEXP_LIKE('e', '[:upper:]')

REGEXP_LIKE('e', '[:lower:]')

Related Oracle docs can be found here:

Oracle – Multilingual Regular Expression Syntax

Oracle – REGEXP_LIKE

Answer 1

The character classes seem to work when you surround them with brackets [] as in :

SQL> SELECT * FROM dual WHERE regexp_like('e', '[[:upper:]]');

DUMMY
-----

SQL> SELECT * FROM dual WHERE regexp_like('E', '[[:upper:]]');

DUMMY
-----
X

When you use single brackets Oracle treats them as a list of characters, i-e the following works because u is contained in the string :upper::

SQL> SELECT * FROM dual WHERE regexp_like('u', '[:upper:]');

DUMMY
-----
X