คำสั่ง php implode นอกจาก รวมตัวอ้กษร ใช้ทำอะไรได้อีกบ้าง

$data = array("a", "b", "c", "d");

$strText = implode(":", $data);

echo $strText;

<?php
 
 $arr = array(
    array( 'id' => 1, 'name' => 'ชัยวัฒน์', 'term' => '2', 'grade' => 'B'),
    array( 'id' => 2, 'name' => 'พิทักษ์', 'term' => '2', 'grade' => 'B+'),
    array( 'id' => 3, 'name' => 'วศิลป์', 'term' => '2', 'grade' => 'C+' ),
    array( 'id' => 4, 'name' => 'กฤษฏา', 'term' => '2', 'grade' => 'A' ),
    array( 'id' => 5, 'name' => 'ณรงค์', 'term' => '2', 'grade' => 'C' ),
    array( 'id' => 6, 'name' => 'วรวุทธิ์', 'term' => '2', 'grade' => 'B+' ),
   );
 //เขียนแบบเดิม
 echo '<table border=1 width=300>';
 echo '<tr><th>รหัส</th><th>ชื่อ</th><th>เทอม</th><th>เกรด</th></tr>';
 foreach($arr as $rs){
  echo "<tr><td>". $rs['id'] ."</td><td>". $rs['name'] ."</td><td>". $rs['term'] ."</td><td>". $rs['grade'] ."</td></tr>";
 }
 echo '</table>';
  
 //เขียนแบบใช้ implode()
 echo '<table border=1 width=300>';
 echo '<tr><th>รหัส</th><th>ชื่อ</th><th>เทอม</th><th>เกรด</th></tr>';
 foreach($arr as $rs){
  echo "<tr><td>". implode("</td><td>", $rs) ."</td></tr>";
 }
 echo '</table>';
?>

<?php
 
 $_POST['id'] = array( 1, 3, 8, 10);//รหัสที่ส่งมาจากฟอร์ม
  
 $inId = "'". implode("', '", $_POST['id']) ."'";
 $sql = "SELECT * FROM my_table WHERE id IN($inId) ";
  
 echo $sql;
  
?>