表过滤结果查询

我希望在输入要搜索的值后过滤结果，以便表头链接只返回搜索结果。目前它返回整个表。我该怎么做呢?通过改变表单从post到get?什么好主意吗?

通常，该表将显示20多条记录，可以通过单击表头对其进行排序。当搜索完成时，我希望表头只对搜索结果进行排序。例如，如果我搜索'Tom'，它返回了3个结果，我希望标题中的链接只对这3个返回的结果进行排序。

<?php

include 'dbconnect.php';
if(isset($_POST['search'])) {
$valueToSearch = mysqli_real_escape_string($db, $_POST['valueToSearch']);
// search in all table columns
// using concat mysql function
$sql = "SELECT * FROM contacts 
        WHERE CONCAT(FirstName, Surname, Email, HomePhone, MobPhone) 
        LIKE '%".$valueToSearch."%'";
$query = mysqli_query($db,$sql);
} else {


$orderBy = "FirstName";
$order = "asc";
 if(!empty($_GET["orderby"])) {
$orderBy = $_GET["orderby"];
}
if(!empty($_GET["order"])) {
$order = $_GET["order"];
}
$firstOrder = "asc";
$SurOrder = "asc";
$emailOrder = "desc";
if($orderBy == "FirstName" and $order == "asc") {
    $firstOrder = "desc";
}
if($orderBy == "Surname" and $order == "asc") {
    $surOrder = "desc";
}
if($orderBy == "Email" and $order == "desc") {
    $emailOrder = "asc";
}
// Build an SQL Query
$sql = "SELECT * from contacts ORDER BY " . $orderBy . " " . $order;

// Run the Query
$query = mysqli_query($db,$sql);
}
?>

    <form action="front-contact.php" method="post">
    <input type="text" name="valueToSearch" placeholder="Value To Search"><br><br>
    <input type="submit" name="search" value="Filter"><br><br>
    <form action='' method=post>
    <table border='1'>
    <tr>
    <th><a href="?orderby=FirstName&order=<?php echo $firstOrder; ?>">First Name</a></th>
    <th><a href="?orderby=Surname&order=<?php echo $surOrder; ?>">Surname</th>
    <th><a href="?orderby=Email&order=<?php echo $emailOrder; ?>">Email Address</th>
    <th>Home Number</th>
    <th>Mobile Number</th>
    </tr>
  <?php
       

        
        // Loop through each returned record and store the data in $row.. // 
    while ($row = mysqli_fetch_assoc($query)) {

    // Output the column-name of $row using the array-notation // 
        echo "<form action='' method=post>";
        echo "<tr>";
        echo "<td>".$row['FirstName']."</td>";
        echo "<td>".$row['Surname']."</td>";
        echo "<td>".$row['Email']."</td>";
        echo "<td>".$row['HomePhone']."</td>";
        echo "<td>".$row['MobPhone']."</td>";
        echo " </form>";
        echo "</tr>";
    }
       echo "</table>";

?>