mysql_query(): supplied argument is not a valid MySQL-Link resource

[aa]

I use the following fragment of code to output datf from MySQL:

=============== =============== =============== =========
$chan = mysql_connect ($db_host, $username, $password);
mysql_select_db ($DB_name, $chan);

$resultid = mysql_query ("select name_ru, description_ru, retail, dealer
from lasershot WHERE le='1'", $chan);
........
=============== =============== =============== =========
This was working fine.

Then I needed to repeat this code (except for the first two lines) several
times, every time for a different value of le

I placed everything starting from lime 3 inside {}, made is a function and
called this function like that:

$chan = mysql_connect ($db_host, $username, $password);
mysql_select_db ($DB_name, $chan);
function write_table()
{
$resultid = mysql_query ("select name_ru, description_ru, retail, dealer
from lasershot WHERE le='1'", $chan);
.......
}
write_table();

Now I am getting this error:
Warning: mysql_query(): supplied argument is not a valid MySQL-Link resource
in /files/home2/andrei/lasershot/pricelist_sql_a nsi_split.php on line 41
(line 41 is the former line 3:
$resultid = mysql_query ("select name_ru, description_ru, retail, dealer
from lasershot WHERE le='1'", $chan);

Why does the argument stopped being valid?

When I moved the first two lines inside the function, the line

$chan = mysql_connect ($db_host, $username, $password);

started generating error:
Warning: mysql_connect() : Can't connect to local MySQL server through socket
'/tmp/mysql.sock' (2) in
/files/home2/andrei/lasershot/pricelist_sql_a nsi_split.php on line 40

Does this mean that mysql_query() and mysql_connect() cannot be called from
within a function?

[Andy Hassall]

Re: mysql_query(): supplied argument is not a valid MySQL-Link resource

On Fri, 14 Jan 2005 23:25:14 -0000, "aa" <aa@virgin.ne t> wrote:
[color=blue]
>I use the following fragment of code to output datf from MySQL:
>
>============== =============== =============== ==========
>$chan = mysql_connect ($db_host, $username, $password);[/color]

You haven't checked for errors, and if this fails, you're just continuing
without a connection. All further MySQL calls will fail.
[color=blue]
>mysql_select_d b ($DB_name, $chan);[/color]

No error checking.
[color=blue]
>$resultid = mysql_query ("select name_ru, description_ru, retail, dealer
>from lasershot WHERE le='1'", $chan);[/color]

No error checking.

For every call to mysql_*, check the return for 'false'. If it's false,
there's an error, mysql_error() tells you what's up, and you generally have to
bail out of the script there since your connect/select database/query have
failed.
[color=blue]
>.......
>============== =============== =============== ==========
>This was working fine.
>
>Then I needed to repeat this code (except for the first two lines) several
>times, every time for a different value of le
>
>I placed everything starting from lime 3 inside {}, made is a function and
>called this function like that:
>
>$chan = mysql_connect ($db_host, $username, $password);
>mysql_select_d b ($DB_name, $chan);
>function write_table()
>{
>$resultid = mysql_query ("select name_ru, description_ru, retail, dealer
>from lasershot WHERE le='1'", $chan);[/color]

$chan isn't in scope here. PHP has a somewhat unusal scoping system. Rather
than global variables always being visible, when you're inside a function you
must bring them into scope using a 'global' statement.

Precede the function call with:

global $chan;
[color=blue]
>......
>}
> write_table();
>
>Now I am getting this error:
>Warning: mysql_query(): supplied argument is not a valid MySQL-Link resource
>in /files/home2/andrei/lasershot/pricelist_sql_a nsi_split.php on line 41
>(line 41 is the former line 3:
>$resultid = mysql_query ("select name_ru, description_ru, retail, dealer
>from lasershot WHERE le='1'", $chan);
>
>Why does the argument stopped being valid?[/color]

Again, PHP's scoping system:

http://uk2.php.net/manual/en/language.variables.scope.php

[color=blue]
>When I moved the first two lines inside the function, the line
>
>$chan = mysql_connect ($db_host, $username, $password);
>
>started generating error:
>Warning: mysql_connect() : Can't connect to local MySQL server through socket
>'/tmp/mysql.sock' (2) in
>/files/home2/andrei/lasershot/pricelist_sql_a nsi_split.php on line 40
>
>Does this mean that mysql_query() and mysql_connect() cannot be called from
>within a function?[/color]

No - once you moved it inside the function, none of $db_host, $username or
$password had values, so it would be taking the defaults (connect to hardcoded
socket name using null username and password), which typically won't work.

--
Andy Hassall / <andy@andyh.co. uk> / <http://www.andyh.co.uk >
<http://www.andyhsoftwa re.co.uk/space> Space: disk usage analysis tool

[aa]

Re: mysql_query(): supplied argument is not a valid MySQL-Link resource

Thanks, Andy, it makes a lot of sense. Even the requirement to expressly
declare a variable as a global one.
However it did not sort my problem out. I played with one variable $db_host:
=============== =============== =============== =========
global $chan, $db_host, $username, $password, $DB_name,$DB_na me;
$db_host = "humbug";
function write_table()
{
$username = "myusername ";
......... $password, $DB_name,$DB_na me are assigned values here
$chan = mysql_connect ($db_host, $username, $password);
if ($chan==false)
mysql_error();
......
}
=============== =============== =====
produces the same error as before:
Warning: mysql_connect() : Can't connect to local MySQL server through socket
'/tmp/mysql.sock' (2) in
/files/home2/andrei/lasershot/pricelist_sql_a nsi_split.php on line 42

However if I move
$db_host = "humbug";
inside the function it works fine. Which means that the global variable are
not seen inside a function, or I declare them wrongly

[aa]

Re: mysql_query(): supplied argument is not a valid MySQL-Link resource

I looked up "PHP and MySQL Web Developement" by Luke Welling and Laura
Thomson.
In the para "Scope of variables" it reads (the book is translated into
Russian and I translate is back into English):
"Variables declared as global in a scenario are seen throughout the
scenario, but not seen from within functions. By default all the variables
declared in a scenario outside functions are global."

It looks like if query MySQL from a function, I will have to put all the
database related variables inside the function. And therefore to open and
close a connection to the database very time I run a query.
In my case I am building a page by sending different queries to the
database.
Opening and closing the connection for every query looks like an unnecessary
overhead.

Can I get round it?

[Paul Barfoot]

Re: mysql_query(): supplied argument is not a valid MySQL-Link resource

Hi aa

When I had my first attempt at using functions in a PHP script I had similar
problems. I got round it by passing all variables outside the function into
it in the function call.

function write_table()
{
$resultid = mysql_query ("select name_ru, description_ru, retail, dealer
from lasershot WHERE le='1'", $chan);
.......
}
write_table();

becomes

function write_table($ch annel)
{
$resultid = mysql_query ("select name_ru, description_ru, retail, dealer
from lasershot WHERE le='1'", $channel);
.......
}
write_table($ch an);

See if that helps.

--
Paul Barfoot

"aa" <aa@virgin.ne t> wrote in message
news:41e8fdb1$0 $22490$ed2619ec @ptn-nntp-reader03.plus.n et...[color=blue]
>I looked up "PHP and MySQL Web Developement" by Luke Welling and Laura
> Thomson.
> In the para "Scope of variables" it reads (the book is translated into
> Russian and I translate is back into English):
> "Variables declared as global in a scenario are seen throughout the
> scenario, but not seen from within functions. By default all the variables
> declared in a scenario outside functions are global."
>
> It looks like if query MySQL from a function, I will have to put all the
> database related variables inside the function. And therefore to open and
> close a connection to the database very time I run a query.
> In my case I am building a page by sending different queries to the
> database.
> Opening and closing the connection for every query looks like an
> unnecessary
> overhead.
>
> Can I get round it?
>
>
>
>[/color]

[aa]

Re: mysql_query(): supplied argument is not a valid MySQL-Link resource

That's and idea. Thanks

[Norman Peelman]

Re: mysql_query(): supplied argument is not a valid MySQL-Link resource

"aa" <aa@virgin.ne t> wrote in message
news:41e854da$0 $41092$ed2e19e4 @ptn-nntp-reader04.plus.n et...[color=blue]
> I use the following fragment of code to output datf from MySQL:
>
> =============== =============== =============== =========
> $chan = mysql_connect ($db_host, $username, $password);
> mysql_select_db ($DB_name, $chan);
>
> $resultid = mysql_query ("select name_ru, description_ru, retail, dealer
> from lasershot WHERE le='1'", $chan);
> .......
> =============== =============== =============== =========
> This was working fine.
>
> Then I needed to repeat this code (except for the first two lines) several
> times, every time for a different value of le
>
> I placed everything starting from lime 3 inside {}, made is a function[/color]
and[color=blue]
> called this function like that:
>
> $chan = mysql_connect ($db_host, $username, $password);
> mysql_select_db ($DB_name, $chan);
> function write_table()
> {
> $resultid = mysql_query ("select name_ru, description_ru, retail, dealer
> from lasershot WHERE le='1'", $chan);
> ......
> }
> write_table();
>
> Now I am getting this error:
> Warning: mysql_query(): supplied argument is not a valid MySQL-Link[/color]
resource[color=blue]
> in /files/home2/andrei/lasershot/pricelist_sql_a nsi_split.php on line 41
> (line 41 is the former line 3:
> $resultid = mysql_query ("select name_ru, description_ru, retail, dealer
> from lasershot WHERE le='1'", $chan);
>
> Why does the argument stopped being valid?
>
> When I moved the first two lines inside the function, the line
>
> $chan = mysql_connect ($db_host, $username, $password);
>
> started generating error:
> Warning: mysql_connect() : Can't connect to local MySQL server through[/color]
socket[color=blue]
> '/tmp/mysql.sock' (2) in
> /files/home2/andrei/lasershot/pricelist_sql_a nsi_split.php on line 40
>
> Does this mean that mysql_query() and mysql_connect() cannot be called[/color]
from[color=blue]
> within a function?
>
>[/color]

You need to:

function write_table()
{
global $chan; // this makes $chan visible to the function.
$resultid = mysql_query ("select name_ru, description_ru, retail, dealer
from lasershot WHERE le='1'", $chan);
......
}


Norm
---
FREE Avatar hosting at www.easyavatar.com