Re: [cx-oracle-users] ORA -24806 error reading NCLOB data

[Chris D. <cdu...@ya...>]

Hi,

Here's a simple test case that produces the ORA-12704 Character set mismatch error

1. The setup SQL

create table nclob_source (col1 nclob);
create table nclob_dest (col1 nclob);
insert into nclob_source values ('dsfdfsdsf');
commit;

2. Python code

def insertCursorNclob():
    c1 = db.cursor()
    c2 = db.cursor()
    c3 = db.cursor()
    sourceVars = c1.execute("select col1 from nclob_source")
    targetVars = c2.setinputsizes(*sourceVars)
    c3.execute("select col1 from nclob_source")
    for row in c3.__iter__():
        print row
        print row[0].read()
        c2.execute("insert into nclob_dest (col1) values(:arg3)", (row[0].read(),))
    print "Success !!!" + "\n"

import cx_Oracle as cx
db = cx.connect("u1/p1@db1")

print "NCLOB insert !"
insertCursorNclob()
db.commit()

3. Output

NCLOB insert !
(<cx_Oracle.LOB object at 0x40295560>,)
dsfdfsdsf
Traceback (most recent call last):
  File "nclob_cx_420.py", line 21, in ?
    insertCursorNclob()
  File "nclob_cx_420.py", line 11, in insertCursorNclob
    c2.execute("insert into nclob_dest (col1) values(:arg3)", (row[0].read(),))
cx_Oracle.DatabaseError: ORA-12704: character set mismatch


BTW standard SQL as follows works fine:

insert into nclob_dest select * from nclob_source;

Hope this helps.

Chris



--- Anthony Tuininga <ant...@gm...> wrote:

> On 7/24/06, Chris Dunscombe <cdu...@ya...> wrote:
> > Hi,
> >
> > I've given it a try and my simple test case now works, thanks. However in my actual
> application I
> > now get an ORA-12704 Character set mismatch error. I need to investigate this one further to
> see
> > exactly what's going on.
> 
> Yes please! I didn't get such difficulties but I set up a rather
> contrived situation since I don't personally use this feature much at
> all -- and then only with single byte character sets such as latin-1.
> 
> > Also with 4.2 I now get lots of Primary key violations on inserts after doing
> cursor.fetchraw()
> > and then inseting the results. The code works fine and as expected with 4.1.2. I'll need to
> some
> > more digging at my end on this as well but it does seem strange to get such different
> behaviour
> > changing from 4.1.2 to 4.2.
> 
> Hmm, that is strange. If you can provide a test case that would be great.
> 
> > Thanks again,
> >
> > Chris
> >
> > --- Anthony Tuininga <ant...@gm...> wrote:
> >
> > > Ok, I've had a chance to look at this and the reason the problem is
> > > occurring is because Oracle wants SQLCS_NCHAR set as the character set
> > > form and does not do so automatically. I've modified cx_Oracle to do
> > > this as needed. There may be additional work that is needed (and I've
> > > added infrastructure to support it) but my initial attempts to bind
> > > NCLOB data appear to work just fine. After this is released (hopefully
> > > very soon) you can check it out and let me know if more work is
> > > needed.
> > >
> > > On 6/9/06, Anthony Tuininga <ant...@gm...> wrote:
> > > > Unfortunately, none at the moment. But I'll take a look at it at some
> > > > point soon and let you know if I find anything. If anyone else has any
> > > > information I'd love to hear about it. My knowledge of Unicode is not
> > > > all that extensive. :-)
> > > >
> > > > On 6/9/06, Chris Dunscombe <cdu...@ya...> wrote:
> > > > > I'm trying to read data from an NCLOB column using:
> > > > >
> > > > > for nclob_col, other_col in cursor.__iter__():
> > > > >     nclob = nclob_col.read()
> > > > >     ......
> > > > >
> > > > > This returns the Oracle error ORA-24806 - Lob form mismatch.
> > > > >
> > > > > Environment is:
> > > > >   cx_Oracle version 4.1.2
> > > > >   Oracle version 9.2.0.7
> > > > >   Python 2.3.3
> > > > >   SuSE Linux 8.2
> > > > >
> > > > > Anyone any ideas?
> > > > >
> > > > > Thanks,
> > > > >
> > > > > Chris Dunscombe
> 
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