Re: [cx-oracle-users] Types used for values returned from a query

[Anthony T. <an...@co...>]

Paul Moore wrote:

>>Oracle is quite happy to accept the string as input to a numeric column. I'm
>>not sure if that will work for you but it is an option.
> 
> 
> Quite possibly. I can just bind the variable as a String in Java, and
> then load it into a Number column, I guess. Could there be any format
> issues (exponential formats, commas in numbers, etc)? I only ask
> because the environemnt makes it annoyingly hard to report errors, so
> when things go wrong it's a real pain to debug :-(

Not certain. Since I've only dumped it for future import into an Oracle 
database that hasn't been an issue for me. You'll have to try -- you can 
find out what happens by simply issuing "to_char(number)" on any number 
you would care to and looking at the resulting string.

>>>Alternatively, is there any likelihood of cxOracle using Python 2.4's
>>>Decimal type in the near future?
>>
>>Theoretically this wouldn't be all that difficult to accomplish but
>>since there is no C implementation this would mean a significant
>>performance penalty.
>>Having used the Decimal type myself in pure Python
>>I know that it is the most efficiently coded module, either. I suppose
>>this type could be returned __only__ if the data is not an integer and
>>that would mitigate the problem somewhat. Comments?
> 
> 
> That may be an option, but frankly, this is pretty specialised use
> where an exact representation is crucial. Maybe just having a way of
> saying that a specific column in a query must be returned as a string,
> and then doing string->Decimal in Python would be suitable. Something
> like
> 
>    c = cn.cursor()
>    c.execute("select...")
>    c.col_as_string(1)
>    row = c.fetchone()
>    decval = Decimal(row[1])
> 
> All I really care about is having some way of being sure that there's
> no precision loss - using strings does it, the rest is just
> convenience (only using strings where it's really needed).
> 
> Sorry - must dash, but I hope you get the idea...

I do and I've considered something similar. Perhaps a 
cursor.define(position, data_type) which would allow you to override the 
default retrieve definition. In your example the call would be 
"c.define(1, cx_Oracle.STRING)". I suspect it would have to take place 
before the execute() call, though. Comments, anyone?

> Paul
> 
> 
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-- 
Anthony Tuininga
an...@co...

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