問題描述

我有一段代碼，根據請求的 URL，將包含其他十四個文件之一.這 14 個文件中的一些需要連接到三個不同數據庫之一，并且可以隨時添加其他文件.

I have a section of code that depending on the URL requested, will include one of fourteen other files. Some of these fourteen files require a connection to one of three different databases, and additional files can be added at anytime.

我不想默認打開所有三個數據庫的 PDO 連接，因為它浪費資源并且會減慢執行時間.所以我的想法是將所有 SQL 查詢包裝在一個函數中.第一次在未打開的 PDO 連接上執行查詢時，try {} 錯誤處理程序可以捕獲它，找出問題所在(在這種情況下連接不存在)，然后打開連接并重新執行詢問.這樣，數據庫只在需要時才連接 - 只要連接字符串(主機、數據庫、用戶名、密碼)都預先定義，我看不出它有任何問題.

I don't want to open PDO connections by default to all three database as its a waste of resources and will slow the execution time down. So my thought is to wrap all SQL queries within a function. The first time that a query is executed on a non-open PDO connection, the try {} error handler can catch it, find out what the problem was (in this case connection doesnt exist), then open the connection and re-execute the query. That way, the database is only being connected to as and when needed - as long as the connection string (host, database, username, password) are all defined in advance, I can't see any problem in it working.

但是，我需要繼續推進，并且在大約 7 天內無法訪問開發箱，所以任何人都可以看出這種情況有什么問題嗎?另外，如果沒有打開連接，誰能告訴我 handler->errorInfo() 將返回的錯誤消息?

However, I need to push on with this, and don't have access to the dev box for about 7 days, so can anyone see any problem with that scenario? Also, can anyone give me the error message that handler->errorInfo() will return if the connection isn't opened?

推薦答案

這是正確的想法，但不是它的最佳實現.

This is the right idea, but not the best implementation of it.

包裝 SQL 操作很好.但是你為什么不這樣做呢:

Wrapping the SQL operations is good. But why don't you do it this way:

class Wrapper {
    private static $db;

    public static function someQuery() {
        $db = self::getDatabase();
        // now go on to execute the query
    }

    private static function getDatabase() {
        if (self::$db === null) {
            self::$db = // connect here
        }
        return self::$db;
    }
}

這有很多優點:

• 允許您在邏輯上將 SQL 操作分組為一個(或多個！)類
• 如果不需要，不連接到數據庫
• 不依賴(脆弱的)錯誤檢查來正常運行

在您的特定情況下，您可能應該使用 3 個單獨的 Wrapper 類.將所有內容都放在一個類中是可行的(三個不同的 $db 變量)，但可能比它的價值更令人困惑.

In your specific case, you should probably go with 3 separate Wrapper classes. Putting everything into one class is doable (three different $db variables) but probably more confusing than it's worth.

這篇關于僅在需要時自動連接到 PDO的文章就介紹到這了，希望我們推薦的答案對大家有所幫助，也希望大家多多支持html5模板網！