[Gambas-user] gb.db local change

[Benoit Minisini]

Le 09/12/2022 à 09:14, BB a écrit :
> I need a bit of help here. In our local version of the interpreter I 
> want to implement a "small" change to use the "RETURNING *" optional SQL 
> command. This works fine for postgresql but not for sqlite (at this 
> stage of debian's distros). I understand (I'm pretty sure) the object 
> model but I can't write the C code.
> 
> Within the following patch I want to test the "THIS->conn->" database 
> type and only include the RETURNING clause if its a PostgreSQL database 
> we are talking to.
> 
> +++ b/main/lib/db/CResult.c
> 
> @@ -716,7 +716,7 @@ BEGIN_METHOD_VOID(Result_Update)
> 
>   			}
> 
>   
> 
>   			q_add(" )");
> 
> +			q_add(" RETURNING * ");              <----- but only if PostgreSQL
> 
> 
>   			if (!THIS->driver->Exec(&THIS->conn->db, q_get(), NULL, "Cannot create record: &1"))
> 
>   				void_buffer(THIS);
> 
> This is a LOCAL change as the RETURNING clause is not universally 
> supported. In fact I'm not sure if it is conformant to the SQL standard, 
> but we really need it here.
> 
> I have had many tries at working this out but have had no success.
> 
> Can anyone help me here, please.
> 
> bruce
> 
This is just for your hack, as it should not be done like that:

if (!strcmp(THIS->driver->name, "postgresql"))
   q_add(" RETURNING *");

The correct way is adding a flag in the 'flags' field of the DB_DATABASE 
structure that tells if we can add "RETURNING", and set that flag in the 
open_database() method of the drivers that support it (with a test on 
the database version possibly).

Regards,

-- 
Benoît Minisini.