敏感词过滤

/*第一种方式*/
$sql="select value from dede_sysconfig where varname='cfg_notallowstr'";

    $mingan=$link->query($sql);

    $arr = $mingan->fetch_row();
    //数组元素组合成字符串
    $list="/".implode("|",$arr)."/i";

    if(preg_match($list,$username,$matches)){ 
        echo "<script>alert('包含敏感词,不能注册');</script>";
    } else { 
        $sql= "insert into dede_member2 (userid,uname,email,pwd,mobile,jointime) values('$username','$username','$email','$hashpwd','$mobile','$jointime')";
        // echo "出错" . $sql . "<br>" . $conn->error;
        //插入数据库
        if(!mysqli_query($link,$sql)){
            // echo strlen($hashpwd); 
            // echo "出错" . $sql . "<br>" . $conn->error;
            echo "<script>alert('数据插入失败');window.location.href='/a/zhuce/index.html'</script>";
        }
        else{
            echo  "<script>alert('注册成功！');window.location.href='/index.php'</script>";  
        } 
    }