Question

I want to insert into mysql database from C.
Here is my code:

…

for (i=0;i<nb_of_subscribers*hits_subscriber;i++)

   { RandomSub= rand() % nb_of_subscribers + 1;
   RandomContent= rand() % (contents_tag*tags) + 1;

    mysql_query(conn, "INSERT INTO CONTENT_HITS(CONTENT_ID,SUBSCRIBER_ID) VALUES(RandomContent,RandomSub)");}

…
The problem is :The insert query is not executed and nothing appears in the database.
Thank you.

Answer 1

How do the values for RandomSub and RandomContent (that you’ve declared) actually get into the query you’re executing? You’re trying to run

INSERT INTO CONTENT_HITS(CONTENT_ID,SUBSCRIBER_ID) VALUES(RandomContent,RandomSub)

which will fail as it’s trying to put two strings into (I guess) two integer fields.

You need to substitute the values of RandomContent and RandomSub into the string:

char q[1024];
for (i=0;i<nb_of_subscribers*hits_subscriber;i++)
{

    RandomSub= rand() % nb_of_subscribers + 1;
    RandomContent= rand() % (contents_tag*tags) + 1;

    sprintf(q,"INSERT INTO CONTENT_HITS(CONTENT_ID,SUBSCRIBER_ID) VALUES(%d,%d)",RandomContent,RandomSub);

    mysql_query(conn, q);
}

As @SpacedMonkey says – you should be using a prepared statement for this

Pretty basic C stuff to be honest.

PS – do some accepts – 10% isn’t great