Handling button events for SQL items [duplicate]

I am trying to display a button next to items that are populated from a mysql database and do something when user clicks on them. What i have so far is :

if ($result->num_rows > 0) {
     echo "<table><tr><th>SERIAL_NO</th><td></td><th>IP</th> 
     <td></td><td></td><th>MAC</th><td></td></tr>";

     while($row = $result->fetch_assoc())
     {
         echo "<style> td {text-align:center;}</style>";
         echo "<tr><td>".$row["serial_no"]."</td><td>"."|"." 
         </td><td>".$row["ip"]."</td><td></td><td>"."|"."</td> 
         <td>".$row["mac"]."</td><td>"."<input type=\"button\" 
         value=\"Rebuild\" onclick=\"rebuild()\" />"."</td> 
         </tr>";

     }
     echo "</table>";
} 
else 
{
    echo "0 results";
}

function rebuild()
{
    echo "The rebuild function is called.";
}

However these button click events are not working. Can somebody please tell me what's the purpose of onclick=func() in php and what is a good simple solution (I don't wanna make it too complicated, all I want is to pass the row index to a function when the button is pressed).

Update: The new code is :

if ($result->num_rows > 0) {
    echo "<style> table, th, td {border: 1px solid black;} 
    </style>";
    echo "<table><tr><th>SERIAL_NO</th><th>IP</th><th>MAC</th> 
    <th>Action</th></tr>";

    while($row = $result->fetch_assoc())
    {
        echo "<style> td {text-align:center;}</style>";
        echo "<tr><td>".$row["serial_no"]."</td> 
         <td>".$row["ip"]." </td>
         <td>".$mac."</td> 
         <td>".'<form>action="file_download.php" method="post"> 
         <input type="submit" name="serial_no" value="' . 
         $serial_no . '"</input></form>' . 
         "</td></tr>";
    }
    echo "</table>";
} 
else 
{
   echo "0 results";
}

With this I am just getting the literal html code on the browser, here is the exact text in these cells: action="file_download.php" method="post"> 10001

Note: 10001 is $serial_no for that row.

source https://stackoverflow.com/questions/67892020/handling-button-events-for-sql-items