无法重定向后mysqli连接错误

Question

我是新来的PHP。我试图重定向到php中的错误页面，当我得到一个MySQL连接错误，但我得到一个错误，指出我不能修改头，因为输出已经在第8行（我创建连接）发送。请你能建议这样做的正确方法吗？

<?php 
$servername = "localhost:3306"; 
$username = "danny"; 
$password = "sql1"; 
$dbname = "testdb"; 

    try{ 
     $conn = new mysqli($servername, $username, $password, $dbname); 
    } 
    catch(Exception $e){ 
    header('Location: /connection_error.php'); 
    die(); 
} 


?> 

感谢

丹尼

Answer 1

你需要在顶部加入这一行告诉mysqli的抛出异常

mysqli_report(MYSQLI_REPORT_STRICT); 
$servername = "localhost:3306"; 
$username = "danny"; 
$password = "sql1"; 
$dbname = "testdb"; 

    try{ 
     $conn = new mysqli($servername, $username, $password, $dbname); 
    } 
    catch(Exception $e){ 
    header('Location: /connection_error.php'); 
    die(); 
} 

Answer 2

试试这个

<?php 
ob_start(); 

$servername = "localhost:3306"; 
$username = "danny"; 
$password = "sql1"; 
$dbname = "testdb"; 

    try{ 
     $conn = new mysqli($servername, $username, $password, $dbname); 
    } 
    catch(Exception $e){ 
    header('Location: /connection_error.php'); 
} 

ob_flush(); 
?> 

Answer 3

此外，你总是可以检查th e使用mysqli::$connect_errno从上次连接呼叫发出的错误代码，但如果失败，则会返回上次呼叫的错误代码值。零意味着没有错误发生（因此错误）。

<?php 
    /* Variable Defaults */ 
    $servername = 'localhost:3306'; 
    $username = 'danny'; 
    $password = 'sql1'; 
    $dbname  = 'testdb'; 

    /* Make Connection */ 
    $conn = new mysqli($servername, $username, $password, $dbname); 

    /* Check Connection */ 
    if($conn->connect_errno) { 
     /* Redirect */ 
     header('Location: /connection_error.php'); 
     exit(); 
    } 
?>