How to implement the paging function of php background table

<?php
  //init.php
  $conn = mysqli_connect(&#39;127.0.0.1&#39;,&#39;root&#39;,&#39;&#39;,&#39;xz&#39;,3306);
  $sql = "SET NAMES UTF8";
  mysqli_query($conn,$sql);
  $pagecount = 3;
?>

<?php
  //用户管理
  echo "用户管理<br/>";
  @$start = $_REQUEST[&#39;start&#39;];
  if($start === null || $start === " "){
    die("start required");
  }
  require("init.php");
  $sql = "SELECT * FROM xz_user LIMIT $start,$pagecount";
  $sql1 = "SELECT uid FROM xz_user";
  $result = mysqli_query($conn,$sql);
  $result1 = mysqli_query($conn,$sql1);
  if($result === false || $result1 === false) {
    echo "执行失败";
  }else {
    //$rowcount = mysqli_affected_rows($conn);
    $arr = mysqli_fetch_all($result,1);
    $rowcount = count($arr);
    echo "查询到的结果行数：" . $rowcount . "<br/>";
    //if($rowcount > 0){
      $arr1 = mysqli_fetch_all($result1,1);
      $count = count($arr1);
      echo "总行数：$count<br/>";
?>
<table border="1">
  <tr>
    <td>用户编号</td>
    <td>用户名</td>
    <td>密码</td>
    <td>邮箱</td>
    <td>电话</td>
    <td>操作</td>
  </tr>
<?php
  for($i=0;$i<count($arr);$i++){
    $tmp = $arr[$i][&#39;uid&#39;];
    echo "
      <tr>
        <td>".$arr[$i][&#39;uid&#39;]."</td>
        <td>".$arr[$i][&#39;uname&#39;]."</td>
        <td>".$arr[$i][&#39;upwd&#39;]."</td>
        <td>".$arr[$i][&#39;email&#39;]."</td>
        <td>".$arr[$i][&#39;phone&#39;]."</td>
        <td><a href=&#39;delete.php?uid=".$tmp."&#39;>删除</a></td>
      </tr>
    ";
   }
?>
</table>
<?php
}
?>
<!-- 传值 AJAX可优化 -->
<a href="user.php?start=0" rel="external nofollow" >首页</a>
<a href="user.php?start=<?php if($start>=3)echo $start-3; else echo $start; ?>" rel="external nofollow" >上页</a>
<a href="user.php?start=3" rel="external nofollow" >2</a>
<a href="user.php?start=6" rel="external nofollow" >3</a>
<a href="user.php?start=9" rel="external nofollow" >4</a>
<a href="user.php?start=12" rel="external nofollow" >5</a>
<a href="user.php?start=15" rel="external nofollow" >6</a>
<a href="user.php?start=<?php echo $start+3; ?>" rel="external nofollow" >下页</a>
<a href="user.php?start=<?php if($count%3==1)echo $count-1; 
elseif($count%3==2) echo $count-2; elseif($count%3==0) echo $count-3; ?>" rel="external nofollow" >尾页</a>
<span>第<?php echo $start/$pagecount+1 ?>页|共<?php $tmp=$count/$pagecount; $tmp1=(int)($count/$pagecount); 
if($tmp>$tmp1) echo $tmp1+1; else echo $tmp1; ?>页</span>

<?php
  //删除用户
  echo "删除用户<br/>";
  @$uid = $_REQUEST[&#39;uid&#39;];
  if($uid === null || $uid === " "){  //这里注意，是||
    die("uid required");
  }
  require(&#39;init.php&#39;);
  $sql = "DELETE FROM xz_user WHERE uid=&#39;$uid&#39;";
  $sql1 = "UPDATE xz_user SET uid=uid-1 WHERE uid > &#39;$uid&#39;";
  $result = mysqli_query($conn,$sql);
  if($result === false){
    echo "执行失败";
  }else{
    $count = mysqli_affected_rows($conn);
    if($count > 0){
      echo "用户删除成功";
      $result1= mysqli_query($conn,$sql1);
      if($result1 === false){
        echo "重排序失败";
      }else{
        echo "重排序成功";
      }
      if($uid % $pagecount == 0)
        Header("Location:user.php?start=$uid");
      if($uid % $pagecount == 1){
        $uid -= 1;
        Header("Location:user.php?start=$uid");
      }
      if($uid % $pagecount == 2){
        $uid -= 2;
        Header("Location:user.php?start=$uid");
      }
    }else{
      echo "要删除的用户不存在";
    }
  }
?>