Regular Expression for finding Latin characters

Question

i have a table "t" with values in column "text" like
"Āniki"
"Ąvatar"
How can I find them using a regular expression?
The real goal is to replace them with their ASCII equivalent.
Ā = A
Č = C
Ĥ = H
etc....

Answer 1

You can set any range in the ascii table by using the expression 'X-Y' in the pattern. It works for symbols too, but you need to find out whether the desired characters you're interested actually form a contiguous range.
You can run the below query to check the ascii table:
SELECT LEVEL ascii_val, chr(LEVEL) chr_column FROM dual CONNECT BY LEVEL < 256;Then you can pick and choose your ranges and verify them as in the following query:
WITH t AS
(SELECT LEVEL ascii_val, chr(LEVEL) chr_column FROM dual CONNECT BY LEVEL < 256)
SELECT ascii_val, chr_column FROM t WHERE regexp_like(chr_column, '[^A-Za-z0-9!-/]');In the example above I chose a range from the ascii 33 ('!') to 47 ('/'), described by the portion '!-/' in the pattern.
To add another range just concatenate it after the slash symbol.
Additionally, for example, if you want to add a range including the symbols:
ASCII CHR
58    :
59    ;
60    <
61    =
62    >
63    ?You can set it up like this instead if you feel it's more easily readable:
WITH t AS
(SELECT LEVEL ascii_val, chr(LEVEL) chr_column FROM dual CONNECT BY LEVEL < 256)
SELECT ascii_val, chr_column
  FROM t
WHERE regexp_like(chr_column, '[^A-Za-z0-9' ||
                               chr(33) || '-' || chr(47) ||
                               chr(58) || '-' || chr(63) ||
                               ']');You need to test this though, as the docs state the behaviour may vary depending on your NLS_SORT settings, by using linguistic ranges rather than byte values. For my settings it seems to work, not sure about everywhere else.
Note: In the POSIX standard, a range includes all collation elements between the start and end of the range in the linguistic definition of the current locale. Thus, ranges are linguistic rather than byte values ranges; the semantics of the range expression are independent of character set. In Oracle Database, the linguistic range is determined by the NLS_SORT initialization parameter.http://download.oracle.com/docs/cd/E11882_01/appdev.112/e10471/adfns_regexp.htm
and
http://download.oracle.com/docs/cd/E11882_01/server.112/e10729/ch5lingsort.htm
You can check your NLS_SORT by querying the userenv:
SQL> select sys_context('USERENV', 'NLS_SORT') from dual;
SYS_CONTEXT('USERENV','NLS_SOR
WEST_EUROPEAN
SQL> If it returns BINARY you need not worry about it.
Otherwise you can check the particular sorting your NLS_SORT will use here:
http://download.oracle.com/docs/cd/E11882_01/server.112/e10729/applocaledata.htm#NLSPG593
Usually symbols are not affected by it as you can see there (my case too for the "west_european" value), but other elements in a string can be affected.
Regards,
Sitja.
Edited by: fsitja on Mar 18, 2010 1:51 PM