[cx-oracle-users] set{input,output}sizes() (changed subject)

[Guido v. R. <gu...@el...>]

> setinputsizes() is used to define what type (and size) of data is
> being bound to the cursor. In most cases cx_Oracle (and other database
> access modules) can guess the type from the type of the Python value
> that is bound but the Python None value (representing null in database
> terms) doesn't have any type that corresponds to any database type.
> Thus, if you want to bind a NULL or anything else (like CLOB/BLOB)
> where the database type and size cannot be implied from the Python
> type and size you want to use setinputsizes().
>=20
> setoutputsizes() is for defining the size of data that is being
> fetched from the database. In particular it is used for variable
> length data (like long and long raw in Oracle) where the size cannot
> be known by retrieving the information from the database. If you never
> use long or long raw (and Oracle recommends that you use CLOB and BLOB
> instead) then you never need to know about this function.
>=20
> Does that help?? How many bonus points do I get?? :-)

Sortof.  I'm surprised that NULL (which is supported in SQL) is unknown
at this level, which makes me wonder if I understand any of the rest!

I guess I'm so comfortable with the abstractions that SQL and Python
provide that I have a hard time understanding the precise nature of the
hoops that you have to jump through to tie the two together; for
example, when inserting a 100K-long string into a table column whose
type is CLOB, why would I have to say that it's a CLOB again?

--Guido van Rossum (home page: http://www.python.org/~guido)