On 11.12.2022 11:17, Tony Locke wrote:
Sorry I'm a bit late to all of this. Here's what pg8000 does, together
with what it sends to PostgreSQL:
cursor.execute("SELECT :1, :2", (6, 0))
# Sent to server: "SELECT $1, $2"
# Result: ['6', '0']
cursor.execute("SELECT :2, :1", (6, 0))
# Sent to server: "SELECT $2, $1"
# Result: ['0', '6']
So the driver pg8000 just replaces ':' with '$' and sends it to the
server, and the server uses each numeric as an index into the parameter
list, and ignores the order in which the placeholders appear in the
statement.
Thanks for the added insight. The above is what we had in mind with
the numeric binding type, even though it is not explicitly spelled
out in PEP 249.
Perhaps I ought to add a footnote to the PEP to explain the mode
in more detail.
On Fri, 2 Dec 2022 at 17:57, Marc-Andre Lemburg <m...@egenix.com
<mailto:m...@egenix.com>> wrote:
On 02.12.2022 18:32, John Stevenson - BGS wrote:
The documents officially state “named” as the paramstyle, but with
cx_Oracle we often use the numeric style with executemany so that
we can insert from lists of tuples. In this context, the useful
“feature” of the numeric paramstyle is that you don’t need to
transform your data into a dictionary.
https://cx-oracle.readthedocs.io/en/latest/api_manual/module.html#cx_Oracle.paramstyle
<https://cx-oracle.readthedocs.io/en/latest/api_manual/module.html#cx_Oracle.paramstyle>
I haven’t tried binding the same value multiple times or using the
placeholders in different orders, though.
cx_Oracle seems to use "named" style, but simply binds by position
when passing in a tuple instead of a dictionary (or keyword args).
At least that's what the docs suggest:
https://cx-oracle.readthedocs.io/en/latest/user_guide/bind.html
<https://cx-oracle.readthedocs.io/en/latest/user_guide/bind.html>
I suppose that using "where a=:2 and b=:1" would still bind the
first parameter value to "a" and the second to "b".
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