我在MySQL中测试外键.目标是防止将id输入table2,这在table1中不存在.我希望使用外键只会导致一行没有插入,但它似乎抛出了这个巨大的错误.我如何在PHP中处理这个？有没有办法让MySQL根本不插入行并返回没有返回的行？

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

Stack trace:

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

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

最佳答案
用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

取自Return Code list

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