php+mysqli实现将数据库中一张表信息打印到表格里

<?php
$mysqli = new MySQLi("localhost","root","123456","liuyan");
if(!$mysqli){
 die($mysqli->error);
}
function showTable($mysqli,$table_name){
 $sql = "select from $table_name";
 $res = $mysqli->query($sql);
 //获取返回总行数和列数
 echo "共有".$res->num_rows."行；共有".$res->field_count."列。";
 //获取表头---从$res取出
 echo "<table border=1><tr>";
 while($field=$res->fetch_field()){
   echo "<th>{$field->name}</th>";
 }
 echo "</tr>";
 //循环取出数据
 while($row=$res->fetch_row()){
  echo "<tr>";
  foreach($row as $value){
   echo "<td>$value</td>";
  }
  echo "</tr>";
 }
 echo "</table>";
 $res->free();
}
showTable($mysqli,"news");
?>