Implementing simple real-time database monitoring and scheduling through PHP CLI_PHP tutorial

Function to be implemented: Monitor the user table. If a new record is added, add it to the user2 table. (Practical applications can be more in-depth, such as related processing of data, etc.)

The following is the PHP code (dbtest.php)

Copy code The code is as follows:

!#/usr/local/php/bin/php
mysql_connect('localhost', 'username', 'password') ;
mysql_select_db("test");
echo 'PID: '.posix_getpid().' '; //Current process PID (under linux)
$old_id = 0;
while (1 )
{
$sql = "SELECT `id` FROM `user` ORDER BY `id` DESC LIMIT 1";
$result = mysql_query($sql);
$item = mysql_fetch_assoc( $result);
$new_id = $item['id'];
$values_arr = array();
for ($i=$new_id; $i>$old_id && $old_id!=0 ; $i--)
{
$sql = "SELECT `name`,`age` FROM `user` WHERE `id`='{$i}' LIMIT 1";
$result = mysql_query($sql);
$item = mysql_fetch_assoc($result);
$name = $item['name'];
$age = $item['age'];
$ values_arr[] = "('{$name}', '{$age}')";
}
if (!emptyempty($values_arr))
{
$values_str = implode( ',', $values_arr);
$sql = "INSERT INTO `user2`(`name`, `age`) VALUES {$values_str}";
mysql_query($sql);
}
$old_id = max($old_id, $new_id);
sleep(3); //Enter the next cycle after 3 seconds
}

There should be nothing to say about the business process , there are a few things to pay attention to:
The first line is the command path that needs to be added in PHP CLI mode, and there are while(1) and sleep(3), and the rest are ordinary PHP code writing methods.
You can run it through the shell command php dbtest.php. I tested it on a virtual machine. Under normal circumstances, the CPU usage is 0% and the memory is 1%.
In actual applications, it can be run in the background:
php dbtest.php &
bg 1
PS: The & command is unclear or even wrong in many places. It just puts the program in the background without actually running it!
By the way, let’s summarize and review the commands related to the front and backend running of Linux

Commands Front and backend Status Usage

& The background is suspended and added after the command

bg background run followed by job number

fg front desk run followed by job number

Ctrl+Z Backstage Pause (key combination)

jobs (View all job numbers) Command

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