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

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