[OpenSIPS-Devel] Understanding MySQL prepared statements: no "SET @variable = XXX" query?

[Bogdan-Andrei Iancu]

Hi Iñaki,

Hmm, hard to tell - what opensips does, is simply to use the API 
functions  from mysql libraries - these functions are doing the actually 
mysql commands (the ones you see on the server side).

I guess the libmysqlclient is handling this references to the prepared 
statements in a totally transparent way for the application using the lib.

On the other hand I never used prepared statements in other way than via 
the libmysqlclient.

Regards,
Bogdan

Iñaki Baz Castillo wrote:
> Hi, when OpenSIPS uses prepared statements it generates queries as follows:
>
> ------------------------------------
> 259 Connect     sip at localhost on opensips
> 259 Query       delete from rls_watchers where expires<1252395816
> 259 Prepare     [1] delete from active_watchers where expires<?
> 259 Execute     [1] delete from active_watchers where expires<1252395816
> ------------------------------------
>
>
> I expected that the above would be in the following way:
>
> ---------------------------------
> 259 Connect     sip at localhost on opensips
> 259 Query       PREPARE ps_name FROM "delete from active_watchers
> where expires<?"
> 259 Prepare     [1] delete from active_watchers where expires<?
> 259 Query       SET @var = 1252395816
> 259 Query       EXECUTE ps_name USING @var
> 259 Execute     [1] delete from active_watchers where expires<1252395816
> ----------------------------------
>
>
> This is, I expected to see a "SET" query as MySQL documentation about
> prepared statements explains:
>   http://dev.mysql.com/tech-resources/articles/4.1/prepared-statements.html
>
> Could I know how it works without using "SET" query? Thanks a lot.
>
>