Foreach嵌套For

<?php
$db=new MySQLi("localhost","账号","密码","数据库名");   //链接数据库
$sql=$db->query("select * from  表名");   //执行SQL语句查询
$arrt=$sql->fetch_all();
 echo"<table border='1' width='100%'>";
foreach($arrt as $v)   //遍历数组 
{
    
      echo "<tr>";
      for($a=开始列数;$a<=结束列数;$a++) 
      {
      echo"<td>$v[$a]</td> ";
      }
      echo"</tr>";  
}

echo "</table>";
?>