[R-sig-DB] Add a "dbSendUpdate" function to DBI?

[Hadley Wickham]

The problem with that approach is that you end up with a lot of code like:

if (!dbBegin(con))  stop(dbGetException())
...
if (!dbExecute(con, sql)) stop(dbGetException())
...
if (!dbCommit(con))  stop(dbGetException())

where the developer is responsible for always checking that the
operation succeeded. If you throw an error, then the code is simpler:

dbBegin(con)
...
dbExecute(con, sql)
...
dbCommit(con)

Given that we're using a language with exceptions, it seems better to
use them, rather than adopting the standard C error handling
mechanism.

Hadley

On Thu, Sep 4, 2014 at 9:45 AM, Peter Meißner
<peter.meissner using uni-konstanz.de> wrote:
> IMHO
>
> the general approach should be:
>
> - as long as R does deliver the the queries to the DB and the DB does give
> response there should never ever be an R error - the function did what it
> should do: making sure things were delivered to DB
>
> - the return than should depend on what the DB said:
>   * 0/TRUE                    - no error, nothing else to say
>   * 1/FALSE                   - DB does complain somehow
>   * text/whatever appropriate - something was returned, ...
>
> - if however connection was lost during the execution of the function so it
> cannot be sure delivery went as expected an error should be issued
>
> Best, Peter
>
>
>
> Am 04.09.2014 16:28, schrieb Denis Mukhin:
>
>> In ROracle we standardized on the second approach, namely always return
>> TRUE, otherwise throw an error.
>>
>> Also since UPDATE is not the only operation that does not return any
>> results (although it might with a RETURNING clause) would a more generic
>> name be more appropriate here? Besides DMLs there are also DDLs. Something
>> like dbExecute(), dbSubmit(), dbSend() ...
>>
>> Denis
>>
>> -----Original Message-----
>> From: Hadley Wickham [mailto:hadley using rstudio.com]
>> Sent: Thursday, September 04, 2014 9:13 AM
>> To: MacQueen, Don
>> Cc: Simon Urbanek; R-sig-DB using r-project.org
>> Subject: Re: [R-sig-DB] Add a "dbSendUpdate" function to DBI?
>>
>> A thought: should dbSendUpdate() return a boolean indicating success, or
>> always return TRUE, otherwise throwing an error?
>>
>> Hadley
>>
>> On Wed, Sep 3, 2014 at 3:59 PM, MacQueen, Don <macqueen1 using llnl.gov> wrote:
>>>
>>> Hadley,
>>>
>>> Since you mentioned DBI 0.3 in a recent email, could I make a request
>>> to add a dbSendUpdate() function to DBI, like the one in RJDBC?
>>>
>>> require(RJDBC)
>>>
>>>> find('dbSendQuery')
>>>
>>> [1] "package:RJDBC" "package:DBI"
>>>
>>>> find('dbSendUpdate')
>>>
>>> [1] "package:RJDBC"
>>>
>>> And from ?dbSendUpdate
>>>
>>>    'dbSendQuery' and 'dbSendUpdate' submit a SQL query to the
>>>    database. The difference between the two is only that
>>>    'dbSendUpdate' is used with DBML queries and thus doesn't return
>>>    any result set.
>>>
>>> I would find this helpful, because I could then use scripts unmodified
>>> with either ROracle or RJDBC.
>>> (I suppose adding it to DBI would mean that the one in RJDBC would
>>> have to be modified.)
>>>
>>>
>>> I have:
>>>
>>> Package Version
>>>    "DBI" "0.3.0"
>>>
>>> Package Version
>>> "RJDBC" "0.2-4"
>>>
>>>
>>> Thanks
>>> -Don
>>>
>>> --
>>> Don MacQueen
>>> Lawrence Livermore National Laboratory
>>> 7000 East Ave., L-627
>>> Livermore, CA 94550
>>> 925-423-1062
>>>
>>
>>
>>
>> --
>> http://had.co.nz/
>>
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>
> --
> Peter Meißner
> Workgroup 'Comparative Parliamentary Politics'
> Department of Politics and Administration
> University of Konstanz
> Box 216
> 78457 Konstanz
> Germany
>
> +49 7531 88 5665
> http://www.polver.uni-konstanz.de/sieberer/home/
>
>
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