php 去掉数组中重复数据库

$array = array('a', 'b', 'c', 'd', 'a', 'b');
$result = array_unique($array);
print_r($result);

$array = array('a', 'b', 'c', 'd', 'a', 'b');
$result = array_keys(array_flip($array));
print_r($result);

<?php
  //连接数据库
  $servername = "localhost";
  $username = "username";
  $passWord = "password";
  $dbname = "myDB";

  $conn = new Mysqli($servername, $username, $password, $dbname);

  //检测连接
  if ($conn->connect_error) {
    die("Connection failed: " . $conn->connect_error);
  }

  //从students表中获取数据
  $sql = "SELECT * FROM students";
  $result = $conn->query($sql);

  //将数据存入一个数组
  $array = array();
  if ($result->num_rows > 0) {
    while($row = $result->fetch_assoc()) {
      $array[] = $row;
    }
  }

  //使用array_unique()函数进行数组去重
  $unique = array_unique($array, SORT_REGULAR);

  //清空旧表
  $sql = "TRUNCATE TABLE students";
  $conn->query($sql);

  //将去重后的数据插入新表
  foreach($unique as $row) {
    $sql = "INSERT INTO students (name,age,grade) VALUES ('" . $row['name'] . "'," . $row['age'] . "," . $row['grade'] . ")";
    $conn->query($sql);
  }

  //关闭数据库连接
  $conn->close();
?>