Hi PJ,
By the look of your language you're using PHP to communicate with
MySQL. Is this assumption correct?
If so you don't need to use that section of the manual - that's the C
API for programmers developing applications in the C or C++ language.
PHP is a whole different ball game and you're right - mysql_store_result
would do nothing for you (PHP wouldn't even recognise it as a function.)
If you are using PHP, you'd be better off looking at the PHP manual
instead - http://uk3.php.net/mysql.
Hope this helps,
Andy
PJ wrote:
Hi Andy,
I still don't understand what is the purpose of calling
mysql_store_result().
I got what I needed this way:
$text = Joe of Egypt;
$sql = SELECT title FROM book WHERE title LIKE '$text';
$result = mysql_query($sql);
if (mysql_num_rows($result) 0) {
echo (We have results);
}
else {echo (Empty!);
}
And if I change the Joe of Egypt to Cleopatra of Egypt the return is
correct also.
So why would I need mysql_store_result()? Don't forget, I'm using a
SELECT query, not INSERT, UPDATE or whatever the third was... :-)
PJ
Did I do something wrong?
Andy Shellam wrote:
Hi PJ,
Having been a C programmer for a while this makes perfect sense to
me. You call mysql_(real)_query to execute the query and get the
results from the server. Because the MySQL library doesn't know when
you've finished with the result-set, you have to tell it to write the
results to memory (mysql_store_result.) This can then be read using
mysql_num_rows and other data retrieval functions.
This sentence in the manual makes this clear:
After you have called mysql_store_result() and gotten back a result
that isn't a null pointer, you can call mysql_num_rows() to find out
how many rows are in the result set.
When you're finished with the result-set you can then use
mysql_free_result to release the memory allocated by the library.
What difficulties are you having with error checking? Most MySQL
functions return NULL if the operation fails - mysql_real_connect,
mysql_store_result etc. Others return non-zero, like
mysql_real_query. All the function documentation in the manual gives
the return codes and how to tell if a call failed.
Personally I've found the MySQL manual the best of any documentation
for systems we use, although I agree an example of a simple
client/query would have been useful.
Regards,
Andy
PJ wrote:
What is this supposed to mean from the manual:
The use of |mysql_num_rows()|
http://dev.mysql.com/doc/refman/5.0/en/mysql-num-rows.html depends on
whether you use |mysql_store_result()|
http://dev.mysql.com/doc/refman/5.0/en/mysql-store-result.html or
|mysql_use_result()|
http://dev.mysql.com/doc/refman/5.0/en/mysql-use-result.html to return
the result set
|mysql_num_rows()|
http://dev.mysql.com/doc/refman/5.0/en/mysql-num-rows.html is intended
for use with statements that return a result set, such as |SELECT|
http://dev.mysql.com/doc/refman/5.0/en/select.html.
Does this mean you have to use
mysql_store_result() before using mysql_num_rows() ? kind of doesn't
make sense to have to do that. And there are no clear cut examples or
explanations...
I do not wish to piss-and-moan but I do find that there is a lot to be
desired in the manual; things that are very ;contradictory and/ or
unclear and certainly lacking in examples.
And please, somebody guide me to some tutorial or something where I can
learn to set up proper error checking so you guys don't have to listen
to my problems. :'(
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