PHP PDO MYSQL- 使用 implode() 更新列中具有多个值的单元格，使用旧值获取新值

Question

I used PDO UPDATE, I am trying to update a column has multiple values, I am using implode() function to separate among values, but the updated value adding new values with old ones,which became duplicating values. The column quali_id in Database: BC,MSc

<?php
$pdo = new PDO("mysql:host=localhost;dbname=myDB",'username','pass');
// Define variables and initialize with empty values
$qual = "";
$qual_err ="";
// Processing form data when form is submitted
if (isset($_POST["id"]) && !empty($_POST["id"])) {
  // Get hidden input value
  $id = $_POST["id"];
  // Validate Qualification
  $input_qual = ($_POST["qual"]);
  if (empty($input_qual)) {
      $qual_err = "Please enter the Qualification amount.";
  } else {
      $qual = implode('، ', $input_qual);
  }
  // Check input errors before inserting in database
  if (empty($qual_err) && empty($spec_err) && empty($asse_err)) {
      // Prepare an update statement
//$sql_clear = "INSERT INTO application_hr (id, qualif_id) VALUES (:id,:qual) ON DUPLICATE KEY UPDATE id=:id, qualif_id=:qual";
      $sql_update = "UPDATE application_hr SET qualif_id=:qual  WHERE id=:id";
      if ($stmt = $pdo->prepare($sql_update)) {
          // Bind variables to the prepared statement as parameters
          $stmt->bindParam(":qual", $qual);
          $stmt->bindParam(":id", $id);
          // Attempt to execute the prepared statement
          if ($stmt->execute()) {
              header("location: index.php");
              exit();
          } else {
              echo "Something went wrong. Please try again later.";
          }
      }
      // Close statement
      unset($stmt);
  }
} else {
  // Check existence of id parameter before processing further
  if (isset($_GET["id"]) && !empty(trim($_GET["id"]))) {
      // Get URL parameter
      $id = trim($_GET["id"]);
 // Prepare a select statement
      $sql = "SELECT * FROM application_hr WHERE id = :id";
      if ($stmt = $pdo->prepare($sql)) {
          // Bind variables to the prepared statement as parameters
          $stmt->bindParam(":id", $param_id);
          // Set parameters
          $param_id = $id;
          // Attempt to execute the prepared statement
          if ($stmt->execute()) {
              if ($stmt->rowCount() == 1) {
                  /* Fetch result row as an associative array. Since the result set contains only one row, we don't need to use while loop */
                  $row = $stmt->fetch(PDO::FETCH_ASSOC);
                  //retrieve from DB to array variable using explode function;
                  $qual = explode('، ', $row["qualif_id"]);
                  print_r($qual);
              } else {
                  // URL doesn't contain valid id. Redirect to error page
                  header("location: error.php");
                  exit();
              }
          } else {
              echo "Oops! Something went wrong. Please try again later.";
          }
      }
      // Close statement
      unset($stmt);
  } else {
      // URL doesn't contain id parameter. Redirect to error page
      header("location: error.php");
      exit();
  }
}
?> 

<form action="<?php echo htmlspecialchars(basename($_SERVER['REQUEST_URI'])); ?>" method="post">
    <!-- /************** Begin Select Statement **************/ -->
    <?php
    $sql = "SELECT * FROM qualif ORDER BY id";
    $result = $pdo->query($sql);
    ?>
    <!--/************** End Select Statement **************/-->
    <div class="form-group <?php echo (!empty($qual_err)) ? 'has-error' : ''; ?>">
        <label>Quali</label>
        <div class="row">
            <select name="qual[]" multiple="" class="ui fluid search selection dropdown">
                <?php foreach ($qual as $qualEx) { ?>

                    <option selected value="<?php echo $qualEx; ?>"><?php echo $qualEx; ?></option>
                <?php } ?>

                <?php
                if ($result->rowCount() > 0) {
                    while ($row = $result->fetch()) {
                        ?>
                        <option value="<?php echo $row['name']; ?>"><?php echo $row['name']; ?></option>
                        <?php
                    }
                    unset($result);
                    ?>
                </select>
                <?php
            } else {
                echo "<p class='lead'><em>No records were found.</em></p>";
            }
            ?>
        </div>
        <span class="help-block"><?php echo $qual_err; ?></span> 
</div> 

the user add PhD to previous seleted BC,MSc The column quali_id Output: BC,MSc,PhD,BCs,MSc Which is adding new data with old ones, not what I expected,

How to get the only updated (selected) values?

Also I tried INSERT INTO... ON DUPLICATE KEY UPDATE same above result.

Answer 1

To remove duplicates from an array you can use array_unique() . In your case you would do this right before your implode statement.

$input_qual = array_unique($input_qual);
$qual = implode(',', $input_qual);