Oracle 10.2 ODBC driver: SQLDescribeCol returns too small a precision for numeric expressions
- From: Wolfram Roesler <wr@xxxxxxx>
- Date: Wed, 25 Jul 2007 12:26:57 +0000 (UTC)
Hello,
I hope this is the correct newsgroup to ask about the Oracle ODBC driver
but I didn't find any better place for this.
Short story: It seems that the Oracle 10.2 ODBC driver returns
wrong (too small) precision values for expressions computed in
SELECT statements.
Long story: I have an application that submits queries to an Oracle
database using the SQLExecDirect/SQLFetch functions. The query contains
both database columns and expressions, like
SELECT colname,
DECODE(col2,0,0,col1/col2)
FROM tablename
WHERE ...
After SQLExecDirect I'm calling SQLDescribeCol for each column and
expression in the query to determine the maximum size of the expected
result:
for(int ColId=...)
{
UCHAR ColName[50+1];
SWORD ColNameLen=0,SQLType=0,Scale=0,Null=0;
UDWORD Prec=0;
rc = SQLDescribeCol(hstmt,ColId,
ColName,sizeof(ColName),&ColNameLen,
&SQLType,&Prec,&Scale,&Null);
...
}
Then, I allocate a buffer of size Scale+Prec+2 bytes and call SQLBindCol
to tell ODBC about the buffer size and address. This has worked flawlessly
for years and across many versions of the Oracle server, client, and ODBC
driver.
Because there's a division, the computed expression has up to 16 digits
after the decimal point. This is fine since SQLDescribeCol returns a
precision of 38 so my buffer is large enough for the result.
Now, with the 10.2 ODBC driver, SQLDescribeCol returns a precision of 15
for that same expression. I thus allocate a buffer of 17 bytes, but
the expression returned by Oracle is 18 bytes long (one digit before the
decimal point, the decimal point itself, and 16 digits following). So,
the result doesn't fit into the buffer, and the query aborts with the
error "SQLSTATE=01004: [Oracle][ODBC]String data, right truncated".
The problem occurs with the Oracle ODBC drivers 10.2.0.1 and 10.2.0.3,
which seems to be the latest 10.2 driver available from Oracle. It
works fine with the 10.1.0.2 driver.
Is this a bug in the 10.2 ODBC driver, or am I doing something wrong?
In either case, what can be done about it?
My platform is Visual Studio 7.0 on Windows XP. The database version is
10.2.
Thanks for any help
W. Rösler
.
- Follow-Ups:
- Prev by Date: problems with Mladen's dump2csv script
- Next by Date: Re: problems with Mladen's dump2csv script
- Previous by thread: problems with Mladen's dump2csv script
- Next by thread: Re: Oracle 10.2 ODBC driver: SQLDescribeCol returns too small a precision for numeric expressions
- Index(es):
Relevant Pages
|
