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Jun 20, 2011 at 10:58pm
Saving a dababase
Hello,
I’m currently working with databases following dbviewer & dbcuelist examples from the sdk.
I’m trying to save datas from the database to a file.
And before implementing my own read/write methods using “SELECT *” queries, I’m wondering if there isn’t an easier option.
I can see that db_open from ext_database.c has an option to read from a file on disk but can’t manage to make it work.
An empty file only rejects any table creation/modification.
I also tried to discover methods from the sqlite object (using its o_messlist) but couldn’t find something usefull.
It seems there’s a “create_backup” method but I’m not sure what it is doing and how to use it.
Any idea ?
Thanks
Léo
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Jun 21, 2011 at 6:06pm
Hi Léo,
Unless you’ve set the attribute to make the database a memory-resident database, then the database is automatically saved to disk and updated after each transaction. No manual saving is required.
Cheers,
Tim
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Jun 21, 2011 at 6:40pm
Hi Tim,
I’ve followed the dbcuelist example, so I’m using “db_open”.
Right now I’m passing NULL as second argument in “db_open”, which, if I understand it correctly in “ext_database.c”, forces the database to be “rambased”.
I’ve tried entering a filename instead, I’ve tried with an existing file and a non-existing file. But then all queries return errors, so I don’t understand what I’m doing wrong.
Thanks
Léo
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Jun 23, 2011 at 5:51pm
In audiounit~ there is a cache of plug-in information stored in a SQLite database in the preferences folder. Here is the code used to create/open that database:
short au_db_path = 0;
char au_db_pathstr[MAX_PATH_CHARS];
t_max_err err = MAX_ERR_NONE;
t_db_result *result = NULL;
// Open the cache of AU info (if it exists) from the last time or create it anew
err = preferences_path("", true, &au_db_path);
if (!err)
path_topotentialname(au_db_path, "aucache.db3", au_db_pathstr, 0);
else
strncpy_zero(au_db_pathstr, "aucache.db3", MAX_PATH_CHARS);
err = db_open(ps___max_audiounit_db__, au_db_pathstr, &s_db);
if (err)
error("audiounit~ could not open cache from %s", au_db_pathstr);
Hope this helps,
Tim
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Jun 23, 2011 at 6:44pm
Thanks Tim,
I’ll take a look.
Anyway, I need to be able to read and write different files for my system (something like a complicated preset system).
I only use the database for the powerful data manipulation SQL it provides.
So I implemented my own read/write methods.
Thanks
Léo
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