删除预处理语句函数的创建及使用

<?php
$host = ‘localhost‘;
$user = ‘root‘;
$pass = ‘‘;
$dbname = ‘db‘;
$charset = ‘utf8‘;
$m = new mysqli($host,$user,$pass,$dbname);
$m->set_charset($charset);
//$tn为表名，$w为条件
function delete($tn,$w=‘1=1‘){
	global $m;
	$stmt = $m->prepare("delete from $tn where $w");
	$stmt->execute();
	$r=$stmt->affected_rows;//影响的行数
	$stmt->free_result();
	$stmt->close();
	return $r;
}