問題描述

我有一個 PHP 表單，可以將數據輸入到我的 MySQL 數據庫中.我的主鍵是用戶輸入的值之一.當用戶輸入表中已存在的值時，MySQL 錯誤Duplicate entry 'entered value' for key 1"被退回.而不是那個錯誤，我想提醒用戶他們需要輸入不同的值.只是一個回顯的消息或其他東西.

I have a PHP form that enters data into my MySQL database. My primary key is one of the user-entered values. When the user enters a value that already exists in the table, the MySQL error "Duplicate entry 'entered value' for key 1" is returned. Instead of that error, I would like to alert the user that they need to enter a different value. Just an echoed message or something.

如何將特定的 MySQL 錯誤轉換為 PHP 消息?

How to turn a specific MySQL error into a PHP message?

推薦答案

要檢查此特定錯誤，您需要找到 錯誤代碼.重復鍵是1062.然后使用 errno() 比較:

To check for this specific error, you need to find the error code. It is 1062 for duplicate key. Then use the result from errno() to compare with:

mysqli_query('INSERT INTO ...');
if (mysqli_errno() == 1062) {
    print 'no way!';
}

關于編程風格的說明
您應該始終設法避免使用幻數(我知道，我是在這個答案中介紹它的人).相反，您可以將已知錯誤代碼 (1062) 分配給一個常量(例如 MYSQLI_CODE_DUPLICATE_KEY).這將使您的代碼更易于維護，因為 if 語句中的條件在 1062 的含義從記憶中消失后的幾個月內仍然可讀:)

A note on programming style
You should always seek to avoid the use of magic numbers (I know, I was the one to introduce it in this answer). Instead, you could assign the known error code (1062) to a constant (e.g. MYSQLI_CODE_DUPLICATE_KEY). This will make your code easier to maintain as the condition in the if statement is still readable in a few months when the meaning of 1062 has faded from memory :)

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