> Any pointers on where to look?
That line says it all really. Your initiallizing connection as a pointer
(denoted by *), you have to treat it accordingly when passing it to
functions. Your function init would look something like this:
MYSQL_RES doquery (MYSQL *connection, char query[100]) {
int state;
MYSQL_RES *result;
state = mysql_query(connection,query);
if (state != 0) {
printf(mysql_error(connection));
return NULL;
}
result = mysql_store_result(connection);
return &result;
}
then, in your code, you would connect like normal, then call the function
like this:
MYSQL_RES *result;
result = doquery(&connection, query);
----- Original Message -----
From: "Seth Northrop" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Monday, May 21, 2001 12:25 PM
Subject: C API; queries within functions.
>
> Hi!
>
> This is probably more of a C inadequacy than a MySQL problem. I'm playing
> around with C with MySQL (I have to date only interfaced with it in
> PHP) and I was curious if anyone had any example code which illustrates
> how you would write functions which return mysql data.
>
> For example, in PHP I might write a simple function like this:
>
> function get_specific_db_column($dbname, $tblname, $pk,
> $pk_val, $colname)
> {
>
> $sql = "SELECT $colname as val
> FROM $dbname.$tblname
> WHERE $pk = '$pk_val'";
> $r = mysql_query($sql);
> while ($row = mysql_fetch_array($r))
> $array[] = $row;
> return $array;
>
> }
>
> But, in C I haven't figured out how to do things like navigate passing the
> MYSQL *mysql init pointer into the function for mysql_query etc.
>
> I can however get a program WITHOUT functions (ie, hardcode the
> query) compiled and working:
>
> // Simple test application
> // for the C Mysql API
>
> #include <sys/time.h>
> #include <stdio.h>
> #include <mysql.h>
>
> #define def_host_name NULL
> #define def_user_name "root"
> #define def_password NULL
> #define def_db_name "reflectivity"
>
> int main (char **arg)
> {
>
> MYSQL_RES *result;
> MYSQL_ROW row;
> MYSQL *connection, mysql;
> int state;
> char colsize=10, rowsize=10;
>
> // connect to the mysql database on internal
> mysql_init(&mysql);
> connection = mysql_real_connect(&mysql, def_host_name,
> def_user_name,
> def_password,
> def_db_name,
> 0, /*port defaut*/
> NULL, /*socket default*/
> 0); /*flag*/
> if (connection == NULL) // check for a connection error
> {
> // print the error message
> printf(mysql_error(&mysql));
> return 1;
> }
> state = mysql_query(connection,"SELECT * from reflectivity.accounts");
> if (state != 0)
> {
> printf(mysql_error(connection));
> return 1;
> }
> // you must call mysql_store_result before we can issue anything else
> result = mysql_store_result(connection);
> printf("Rows: %d\n", mysql_num_rows(result));
> // process each row in the result set
> while ((row = mysql_fetch_row(result)) != NULL)
> printf("%s - %s - %s - %s - %s\n",row[0],row[1],row[2],row[3],row[4]);
> // free some memory
> mysql_free_result(result);
> // close the mysql connection
> mysql_close(connection);
> printf("Done.\n");
> }
>
> Ny guess is that if I just see a couple of examples which mimic some of
> the functionality of the above PHP function in C I'll be able to write
> them without a problem.
>
> Any pointers on where to look?
>
> Thanks!
> Seth
>
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