How to handle MySQL's Foreign Key Error in Php?

Question

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?

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

Answer 1

use try catch

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

Read PDOStatement::errorCode

taken from 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