Must COMMIT after SELECT

M.-A. Lemburg mal at egenix.com
Thu Feb 7 17:21:27 CET 2008


On 2008-02-07 16:46, Carsten Haese wrote:
> On Thu, 2008-02-07 at 16:33 +0100, M.-A. Lemburg wrote:
>> mxODBC has support for named cursors that you can later
>> use for positioned updates. 
> 
> Since we're on the topic of shameless plugs, InformixDB has this
> feature, too :)
> 
>> However, it's usually better to do updates in the classical
>> way, ie. by referencing a primary key.
> 
> That depends on the notion of "better". It's entirely possible that a
> "WHERE CURRENT OF <cursor>" clause finds the row in question faster than
> even an indexed access using a primary key could. If you're processing a
> single row, I would agree that using an update cursor is overkill, but
> if you're processing a large number of rows, using an update cursor
> might be beneficial.

Agreed.

This approach is also very useful if you have to do extra analysis
of the rows in question *outside* the database, before selecting them
for update.

-- 
Marc-Andre Lemburg
eGenix.com

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