我不明白为什么我删除第14行($ this-> close();)中的代码,它没有错误,但我不删除它然后警告mysqli_query():无法获取mysqli 。它在最后构造? 我的错误:enter image description here 我的代码:为什么警告:mysqli_query():无法获取mysqli?
<?php
class Display extends Awebarts
{
private $conn;
private $tablename;
public function __construct($tablename)
{
$this->tablename = $tablename;
$this->connectToDb();
$this->conn = $this->getConn();
// insert the data into the table
$this->getData();
$this->close();
}
function getData()
{
$query = "SELECT * FROM $this->tablename ORDER BY `id` DESC LIMIT 1 ";
if(!$sql = mysqli_query($this->conn, $query)) {
throw new Exception("Error: Can not excute the query.");
} else {
$num = mysqli_num_rows($sql);
while($num > 0) {
//var_dump($data);
$data = mysqli_fetch_array($sql);
$num--;
}
}
return $data;
}
}
class Awebarts
{
private $cxn;
private $conn;
function connectToDb()
{
include "models/Database.php";
$vars = "include/vars.php";
$this->cxn = new Database($vars);
$this->conn = $this->cxn->getConn();
}
function getConn()
{
return $this->conn;
}
function close()
{
$this->cxn->close();
}
}
class Database
{
private $host;
private $user;
private $password;
private $database;
private $conn;
function __construct($filename)
{
if(is_file($filename)) {
include $filename;
} else {
throw new Exception("Error");
}
$this->host = $host;
$this->user = $user;
$this->password = $password;
$this->database = $database;
$this->connect();
$this->selectData();
}
function getConn()
{
return $this->conn;
}
private function connect()
{
// connect to the sercer
if(!mysqli_connect($this->host, $this->user, $this->password)) {
throw new Exception("Error: not connected to the server");
} else {
$this->conn = mysqli_connect($this->host, $this->user, $this->password);
}
return $this->conn;
}
private function selectData()
{
if(!mysqli_select_db($this->conn, $this->database)) {
throw new Exception("Error: No database");
}
}
function close()
{
mysqli_close($this->conn);
}
}
?>
所以'close'有个问题吗?给我们看怎么样? –
也请提供完整的错误信息。 –
如果没有完整的错误,任何事情都只是一个猜测,但试着在查询中的'$ this-> tablename'周围放置大括号'{}'。 – aynber