database class problems!!!

sicksound

hey.

i have taken on this big project, and decided it would be a great one to start learning OOP, and it is. things are so much more organized and modular and awesome.

but with my limited experience of class variables and public/private -ness in php, i think i've made a mistake. but i'm not sure.. i'm getting this error:

"Warning: mysql_close(): 6 is not a valid MySQL-Link resource in /var/www/html/cmce/classes/DatabaseConnection.class.php on line 49"

which is not actually an error in my database class, but an error when it trys to execute that function of the database class. on any other page using the database connection i do not have this problem. but here's what i think could be part of the problem:

this particular page has about 4 different objects being built within each, or as a member of each other (?). each of these objects relies on a database connection to build their properties. so, at one time there is a database connection that opens, and then another, and then another, and then it closes, and then the previous one closes, and then the first one closes, you see? so, here's what i'm thinking, please point me in the right direction:

this is just not allowed and i should not be doing this? (please say no?)
whenever i build a new database object i ALWAYS call it $db_connection. now if there are 3-4 different objects, all called $db_connection, is that my problem? and if so, why would it be if they are objects built within a class, meaning (i think?) that naming them the same should not matter?

well, i'm finished blabbing, sorry about the longity of this message, but i'd really appreciate any opinions!

thanks!

sicksound

p.s. i'm not really mad, just frustrated

Shrike

mysql_close() shouldn't be affected by class scope I don't think. However, why bother creating so many links? PHP will fall back to the last opened one in any case.

sicksound

that's what i was thinking too, just opening a link and then having everyone use it. but the problem is, i wont know how far down the heirarchy one class will be at a time, so i will have no way to relate to it dynamically. plus, i'd rather have a connection made inside each class cause then i know i wont have to start a new connection and keep it open on every page. i just have a new one when i need it, you know?

thanks for the mysql_close() tip, that will save me some serious editing!

this thing is making me crraazzzyy!!!

Shrike

Move the SQL connection outside of the class structure then, as I said there are no scoping issues with an SQL connection (unless you absolutely have to refer to a link by name)

sicksound

yeah, you're right, that's probably the best idea. i'll just include a connection and close in the header/footer. it just feels like if i do that there's a little more security risk, or just problem risk? or am i just being paranoid?

Shrike

If the code is going to be processing for a long time (i.e. 15 seconds+) and making database calls at the start and end then it might be a good idea to close connections and reopen them.

I'd say trying to keep track of links opening and closing in a changing class structure would be more of a problem risk 😉

As for security, there's not any difference, although sending credentials once is probably better than sending them n times.

sicksound

excellent! you have been much help!

i think the longest i'm processing, or will be, is maybe 3-4 seconds, so i should be fine.

i just wanted some good convincing before i went and deleted all the open close connections in my classes, haha. but yeah, you are making lots of sense, very good points!

thanks so much!

p.s. one more question, just a refresher:
so i can just use mysql query functions anywhere and it will relate back to the open connection, correct? no link caling needed?
thanks!

Shrike

Yep that's correct.

In actual fact lookin at the manual page, it seems that if you make a 2nd call to mysql_connect() using the same argument list as the first, then the first link gets used anyway, so you might be complicating your code for no reason 😉

sicksound

aha!

ok, i am now making the switch!

thanks!