Getting raw SQL query string from PDO prepared statements

Question

Is there a way to get the raw SQL string executed when calling PDOStatement::execute() on a prepared statement? For debugging purposes this would be extremely useful.

Answer 1

I know this question is a bit old, but, I'm using this code since lot time ago (I've used response from @chris-go), and now, these code are obsolete with PHP 7.2

I'll post an updated version of these code (Credit for the main code are from @bigwebguy, @mike and @chris-go, all of them answers of this question):

/**
 * Replaces any parameter placeholders in a query with the value of that
 * parameter. Useful for debugging. Assumes anonymous parameters from 
 * $params are are in the same order as specified in $query
 *
 * @param string $query The sql query with parameter placeholders
 * @param array $params The array of substitution parameters
 * @return string The interpolated query
 */
public function interpolateQuery($query, $params) {
    $keys = array();
    $values = $params;

    # build a regular expression for each parameter
    foreach ($params as $key => $value) {
        if (is_string($key)) {
            $keys[] = '/:'.$key.'/';
        } else {
            $keys[] = '/[?]/';
        }

        if (is_array($value))
            $values[$key] = implode(',', $value);

        if (is_null($value))
            $values[$key] = 'NULL';
    }
    // Walk the array to see if we can add single-quotes to strings
    array_walk($values, function(&$v, $k) { if (!is_numeric($v) && $v != "NULL") $v = "\'" . $v . "\'"; });

    $query = preg_replace($keys, $values, $query, 1, $count);

    return $query;
}

Note the change on the code are on array_walk() function, replacing create_function by an anonymous function. This make these good piece of code functional and compatible with PHP 7.2 (and hope future versions too).