"Tom Lane" <tgl@xxxxxxxxxxxxx> writes:
> Michael Meskes <meskes@xxxxxxxxxxxxxx> writes:
>> According to the docs parameters are referenced as $1, $2, and so. Is
>> there a reason not to use "?" as placeholder?
>
> It's an operator name.
Most drivers such as JDBC and DBD::Pg do allow you to use ? parameters because
they're the ODBC standard. But they're just replacing them with $1 and so on
behind your back. If you want your code to be portable to other databases then
it makes sense to use ?
But otherwise there are a few advantages to using $1, $2... a) You can change
your query to possibly use the arguments in a different order without having
to change the execute parameters as well. b) You can use a parameter multiple
times in a query without having to burden your execute call site with multiple
copies of the parameter.
I think you lose if you have an operator ? and want to use these drivers
though. Even if you only use $n parameters the driver may still get confused.
(At the very least if you ever have a query with no parameters and a ?
operator in it).
--
Gregory Stark
EnterpriseDB http://www.enterprisedb.com
---------------------------(end of broadcast)---------------------------
TIP 9: In versions below 8.0, the planner will ignore your desire to
choose an index scan if your joining column's datatypes do not
match
|
