如何使用PHP页面中的shell脚本执行MySQL命令？

I want to execute a shell script from php page which will execute a MySQL command.

To do this I followed the way shown here: https://stackoverflow.com/a/8055745/2117868

Here is my sqlscript.sh

#!/bin/sh
sudo wget -t 50 -O /tmp/update.sql http://example.com/update.sql
if [ $? -eq 0 ]; then
    mysql -h "localhost" -u "root" "-pXXXXXXXX" "database-name" < "/tmp/update.sql"
    if [ $? -eq 0 ]; then
        sudo rm /tmp/update.sql
        echo "200"
    else
        echo "502"
    fi
else
    echo "404"
fi

And my php page is runscript.php

<?php
    shell_exec("sudo /path/to/script/sqlscript.sh");
?>

Now, when I'm calling the sqlscript.sh from the server console or php page runscript.php it works perfectly and returns 200 as expected.

But when I take MYSQL user and password in ~/.my.cnf so I don't have to put it on the command-line at all:

[client]
user = root
password = XXXXXXXX

And added credentials in sudoer to execute this script without password.

User_Alias WWW_USER = www-data
Cmnd_Alias WWW_COMMANDS_SQL = /path/to/script/sqlscript.sh
WWW_USER ALL = (ALL) NOPASSWD: WWW_COMMANDS_SQL

Here is my sqlscript.sh

#!/bin/sh
sudo wget -t 50 -O /tmp/update.sql http://example.com/update.sql
if [ $? -eq 0 ]; then
    mysql -h "localhost" "database-name" < "/tmp/update.sql"
    if [ $? -eq 0 ]; then
        sudo rm /tmp/update.sql
        echo "200"
    else
        echo "502"
    fi
else
    echo "404"
fi

Now, when I'm calling the sqlscript.sh from the server console it works perfectly and returns 200 as expected. But if I call it from the php page

http://example.com/runscript.php

it returns 502 as it couldn't execute the SQL command.

Update:

Here is the Apache error.log

--2014-12-05 10:51:55--  http://example.com/update.sql
Resolving example.com (example.com)... 162.144.71.XXX
Connecting to example.com (example.com)|162.144.71.XXX|:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: 146 [text/x-sql]
Saving to: `/tmp/update.sql'

     0K                                                       100% 10.9M=0s

2014-12-05 10:51:55 (10.9 MB/s) - `/tmp/update.sql' saved [146/146]

ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: NO)

So, please help me to solve the issue.