如何檢測MySQL數據庫是否正在運行？

Question

我正在使用XAMPP，我想檢測MySQL數據庫是否正在運行。我的代碼如下所示：

$this->connection = mysqli_connect(
     $this->host, 
     $this->name, 
     $this->pass, 
     $this->db 
); 

if ($this->connection->connect_errno) 
{ 
     $this->connection = false; 
     return false; 
} else { $this->connection->set_charset('utf-8'); } 

我收到以下日誌：

PHP Warning: mysqli_connect(): (HY000/2002): Connection refused ...

PHP Notice: Trying to get property of non-object in // This refers to $this->connection->connect_errno

PHP Fatal error: Call to a member function set_charset() on boolean

我如何避免這種情況？我如何檢查一般數據庫是否可用？

Answer 1

首先，您需要禁用警告報告或將其屏蔽爲mysqli_connect調用，或將其嵌入到try/catch塊中。

然後，而不是檢查connect_errno，而是首先驗證connection是真值。像這樣

$this->connection = false; 
try { 
    $this->connection = mysqli_connect(
      $this->host, 
      $this->name, 
      $this->pass, 
      $this->db 
    ); 
    if (!$this->connection || $this->connection->connect_errno) 
    { 
     $this->connection = false; 
     return false; 
    } else { 
     $this->connection->set_charset('utf-8'); 
    } 
} catch ($e) { //something bad happened. Probably not recoverable. 
    $this->connection = false; 
    return false; 
} 

Answer 2

I am not the author of this answer, it's just the original version of the other post, which is the only correct solution for the conditions given

首先，你想要麼禁用警告報告或抑制它們mysqli_connect電話。

然後，而不是檢查connect_errno，首先驗證connection是真值。像這樣

$this->connection = @mysqli_connect(//<-- warnings suppressed 
     $this->host, 
     $this->name, 
     $this->pass, 
     $this->db 
); 

if (!$this->connection || $this->connection->connect_errno) //lazy evaluation will prevent any issues here 
{ 
     $this->connection = false; 
     return false; 
} else { $this->connection->set_charset('utf-8'); }