如何处理PHP中的MySQL外键错误? [英] How to handle MySQL's Foreign Key Error in Php?

问题描述

我正在测试MySQL中的外键.目的是防止id进入table1中不存在的table2.我希望使用foreign keys只会导致未插入行，但似乎引发了这个巨大的错误.如何在PHP中处理此问题?有没有一种方法可以使MySQL简单地不插入行并且不返回任何返回的行?

I was testing foreign keys in MySQL. The objective is to prevent the entry of an id into table2, that does not exist in table1. I was hoping that using foreign keys would simply result in a row not being inserted, but it seems to throw up this huge error. How do I handle this in PHP? Is there a way to make MySQL simply not insert the row and return no rows returned?

致命错误:消息为'SQLSTATE [23000]的未捕获异常'PDOException':违反完整性约束:1452无法添加或更新子行:外键约束失败(wp-db.borrowed，CONSTRAINT borrowed_ibfk_1 C:\ web \ apache \ htdocs \ dev \ foreign.php:10

Fatal error: Uncaught exception 'PDOException' with message 'SQLSTATE[23000]: Integrity constraint violation: 1452 Cannot add or update a child row: a foreign key constraint fails (wp-db.borrowed, CONSTRAINT borrowed_ibfk_1 FOREIGN KEY (employeeid) REFERENCES employee (id) ON DELETE CASCADE ON UPDATE CASCADE)' in C:\web\apache\htdocs\dev\foreign.php:10

堆栈跟踪:

#0 C:\ web \ apache \ htdocs \ dev \ foreign.php(10):PDOStatement-> execute()

#0 C:\web\apache\htdocs\dev\foreign.php(10): PDOStatement->execute()

在第10行的C:\ web \ apache \ htdocs \ dev \ foreign.php中抛出#1 {main}

#1 {main} thrown in C:\web\apache\htdocs\dev\foreign.php on line 10

推荐答案

使用try catch

use try catch

try { 
    $pdo->exec ("QUERY WITH SYNTAX ERROR"); 
} catch (PDOException $e) { 
    if ($e->getCode() == '23000') 
        echo "Syntax Error: ".$e->getMessage(); 
}

阅读 PDOStatement::errorCode

摘自返回代码列表

SQL-92标准定义了一组SQLSTATE返回代码. SQLSTATE 定义为五个字符的字符串，其中最左边的两个 字符定义错误类别，其余三个字符 定义错误子类.一些数据库供应商可能会扩展这些 返回码；以数字5到9开头的课程，以及 字母I到Z保留用于此类实现特定的 扩展名.特定JDBC操作的SQLSTATE代码可以是 通过SQLException

The SQL-92 standard defines a set of SQLSTATE return codes. SQLSTATE is defined as a five-character string, where the leftmost two characters define the error class, and the remaining three characters define the error subclass. Some database vendors may extend these return codes; classes beginning with the numbers 5 through 9 and letters I through Z are reserved for such implementation-specific extensions. The SQLSTATE code for a particular JDBC action can be retrieved via the getSQLState() method of SQLException

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