Hi, guys.
Dennis Cote wrote:
Stephen,
You should look into using the newer prepare/step API functions
instead of the callback mechanism. It will make your code clearer, and
will probably execute faster as well.
I don't think so. Prepare/step mechanism can invoke productivity of
"INSERT" or "UPDATE", or something like this, when you have much rows to
insert/update. But when you need to do "SELECT" sqlite3_exec - the best
way in my opinion. Look at the code that you represent - this is the
answer on all questions. Want you or don't, but you must allocate memory
for result and call function in C/C++ is very cheaply operation. You
sad: "It will make your code clearer". I don't agree. Look...
char * sql = sqlite3_mprintf( "SELECT * FROM %s", table_name );
int ret = sqlite3_exec( db, sql, callback, NULL, NULL );
sqlite3_free( sql );
What can be clearer than it???
But when you store many information in DB than transactions/prepare/step
are more preferable for productivity. But it does not make code clearer,
inside out...
The new API is used to implement the current version of sqlite3_exec
that uses the callback mechanism so you can look at that code to see
how the new API is used. The following excerpt is from the file
legacy.c in the sqlite source. It shows how sqlite uses the new API
functions to build the arrays of strings it passes to the callback
function.
By using the new API functions directly you can avoid the overhead of
converting all the database fields into string and building these
arrays, only to have your callback function iterate over the string
arrays and convert the values back into other types (for non string
fields anyway) and then stuff them into vectors. You can extract the
fields and store them directly into the vectors you want.
And here I see this magic word "callback" :)
--
Regards,
Igor Mironchick,
Intervale ©
#ICQ 492-597-570
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