Finding and removing non ascii characters from an Oracle Varchar2

Question

We are currently migrating one of our oracle databases to UTF8 and we have found a few records that are near the 4000 byte varchar limit. When we try and migrate these reco

Answer 1

I think this will do the trick:

SELECT REGEXP_REPLACE(COLUMN, '[^[:print:]]', '')

Answer 2

I had similar requirement (to avoid this ugly ORA-31061: XDB error: special char to escaped char conversion failed. ), but had to keep the line breaks.

I tried this from an excellent comment

'[^ -~|[:space:]]'

but got this ORA-12728: invalid range in regular expression .

but it lead me to my solution:

select t.*, regexp_replace(deta, '[^[:print:]|[:space:]]', '#') from  
    (select '-   <- strangest thing here, and I want to keep line break after
-' deta from dual ) t

displays (in my TOAD tool) as

• replace all that ^ => is not in the sets (of printing [:print:] or space |[:space:] chars)

Answer 3

Try the following:

-- To detect
select 1 from dual
where regexp_like(trim('xx test text æ¸¬è© ¦ “xmx” number²'),'['||chr(128)||'-'||chr(255)||']','in')

-- To strip out
select regexp_replace(trim('xx test text æ¸¬è© ¦ “xmxmx” number²'),'['||chr(128)||'-'||chr(255)||']','',1,0,'in')
from dual

Answer 4

Answer given by Francisco Hayoz is the best. Don't use pl/sql functions if sql can do it for you.

Here is the simple test in Oracle 11.2.03

select s
     , regexp_replace(s,'[^'||chr(1)||'-'||chr(127)||']','') "rep ^1-127"
     , dump(regexp_replace(s,'['||chr(127)||'-'||chr(225)||']','')) "rep 127-255"
from (
select listagg(c, '') within group (order by c) s
  from (select 127+level l,chr(127+level) c from dual connect by level < 129))

And "rep 127-255" is

Typ=1 Len=30: 226,227,228,229,230,231,232,233,234,235,236,237,238,239,240,241,242,243,244,245,246,247,248,249,250,251,252,253,254,255

i.e for some reason this version of Oracle does not replace char(226) and above. Using '['||chr(127)||'-'||chr(225)||']' gives the desired result. If you need to replace other characters just add them to the regex above or use nested replace|regexp_replace if the replacement is different then '' (null string).

Answer 5

The select may look like the following sample:

select nvalue from table
where length(asciistr(nvalue))!=length(nvalue)  
order by nvalue;

Answer 6

I found the answer here:

http://www.squaredba.com/remove-non-ascii-characters-from-a-column-255.html

CREATE OR REPLACE FUNCTION O1DW.RECTIFY_NON_ASCII(INPUT_STR IN VARCHAR2)
RETURN VARCHAR2
IS
str VARCHAR2(2000);
act number :=0;
cnt number :=0;
askey number :=0;
OUTPUT_STR VARCHAR2(2000);
begin
str:=’^'||TO_CHAR(INPUT_STR)||’^';
cnt:=length(str);
for i in 1 .. cnt loop
askey :=0;
select ascii(substr(str,i,1)) into askey
from dual;
if askey < 32 or askey >=127 then
str :=’^'||REPLACE(str, CHR(askey),”);
end if;
end loop;
OUTPUT_STR := trim(ltrim(rtrim(trim(str),’^'),’^'));
RETURN (OUTPUT_STR);
end;
/

Then run this to update your data

update o1dw.rate_ipselect_p_20110505
set NCANI = RECTIFY_NON_ASCII(NCANI);