PHP - 在try ... catch ... finally块中关闭MySQLi连接

时间:2017-02-04 18:56:01

标签: php mysqli connection try-catch-finally

try... catch... finally块中关闭MySQLi连接的最佳方法是什么?

这似乎总体上有效,但在第一个if语句失败时会出错(Warning: mysqli::close(): Couldn't fetch mysqli in /path-to-file/ on line 33

以下是代码:

<?php
    session_start();

    if (isset($_POST["login-submit"])) {
        require("db-config.php");

        try {
            $mysqli = @new mysqli($dbHost, $dbUser, $dbPass, $dbName);
            if ($mysqli->connect_error) {
                throw new Exception("Cannot connect to the database: ".$mysqli->connect_errno);
            }

            $username = $_POST["login-username"];
            $password = $_POST["login-password"];

            if (!($stmt = @$mysqli->prepare("SELECT * FROM users WHERE username = ?"))) {
                throw new Exception("Database error: ".$mysqli->errno);
            }

            if (!@$stmt->bind_param("ss", $username)) {
                throw new Exception("Bind error: ".$mysqli->errno);
            }

            if (!@$stmt->execute()) {
                throw new Exception("Execution error: ".$mysqli->error);
            }

        } catch (Exception $exception) {
            $error = $exception->getMessage();
            echo $error; #for debugging

        } finally {
            if ($mysqli != null) $mysqli->close();
            if ($stmt != null) $stmt->close();
        }
    }
?>

1 个答案:

答案 0 :(得分:0)

根本不要关闭它!在脚本末尾没有必要手动关闭连接。一旦执行脚本,连接将自动关闭(如果曾经打开过的话)。您的代码还存在其他问题。

try-catch在您的代码中没有实际目的。只需将其删除。而且,仅手动抛出异常而使mysqli错误静音是没有意义的。您根本没有增加任何价值,相反,您只是在创建混乱的代码。

您修复的示例应如下所示:

<?php

session_start();

if (isset($_POST["login-submit"])) {
    require "db-config.php";

    mysqli_report(MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT);
    $mysqli = new mysqli($dbHost, $dbUser, $dbPass, $dbName);
    $mysqli->set_charset('utf8mb4');

    $username = $_POST["login-username"];
    $password = $_POST["login-password"];

    $stmt = $mysqli->prepare("SELECT * FROM users WHERE username = ?");
    $stmt->bind_param("s", $username);
    $stmt->execute();
}

通过切换自动错误报告,您可以确保如果发生错误,将引发异常。异常就像一个错误,它将停止您的脚本。当脚本执行停止时,PHP将清理并关闭连接。