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

You can extend PDOStatement class to capture the bounded variables and store them for later use. Then 2 methods may be added, one for variable sanitizing ( debugBindedVariables ) and another to print the query with those variables ( debugQuery ):

class DebugPDOStatement extends \PDOStatement{
  private $bound_variables=array();
  protected $pdo;

  protected function __construct($pdo) {
    $this->pdo = $pdo;
  }

  public function bindValue($parameter, $value, $data_type=\PDO::PARAM_STR){
    $this->bound_variables[$parameter] = (object) array('type'=>$data_type, 'value'=>$value);
    return parent::bindValue($parameter, $value, $data_type);
  }

  public function bindParam($parameter, &$variable, $data_type=\PDO::PARAM_STR, $length=NULL , $driver_options=NULL){
    $this->bound_variables[$parameter] = (object) array('type'=>$data_type, 'value'=>&$variable);
    return parent::bindParam($parameter, $variable, $data_type, $length, $driver_options);
  }

  public function debugBindedVariables(){
    $vars=array();

    foreach($this->bound_variables as $key=>$val){
      $vars[$key] = $val->value;

      if($vars[$key]===NULL)
        continue;

      switch($val->type){
        case \PDO::PARAM_STR: $type = 'string'; break;
        case \PDO::PARAM_BOOL: $type = 'boolean'; break;
        case \PDO::PARAM_INT: $type = 'integer'; break;
        case \PDO::PARAM_NULL: $type = 'null'; break;
        default: $type = FALSE;
      }

      if($type !== FALSE)
        settype($vars[$key], $type);
    }

    if(is_numeric(key($vars)))
      ksort($vars);

    return $vars;
  }

  public function debugQuery(){
    $queryString = $this->queryString;

    $vars=$this->debugBindedVariables();
    $params_are_numeric=is_numeric(key($vars));

    foreach($vars as $key=>&$var){
      switch(gettype($var)){
        case 'string': $var = "'{$var}'"; break;
        case 'integer': $var = "{$var}"; break;
        case 'boolean': $var = $var ? 'TRUE' : 'FALSE'; break;
        case 'NULL': $var = 'NULL';
        default:
      }
    }

    if($params_are_numeric){
      $queryString = preg_replace_callback( '/\?/', function($match) use( &$vars) { return array_shift($vars); }, $queryString);
    }else{
      $queryString = strtr($queryString, $vars);
    }

    echo $queryString.PHP_EOL;
  }
}


class DebugPDO extends \PDO{
  public function __construct($dsn, $username="", $password="", $driver_options=array()) {
    $driver_options[\PDO::ATTR_STATEMENT_CLASS] = array('DebugPDOStatement', array($this));
    $driver_options[\PDO::ATTR_PERSISTENT] = FALSE;
    parent::__construct($dsn,$username,$password, $driver_options);
  }
}

And then you can use this inherited class for debugging purpouses.

$dbh = new DebugPDO('mysql:host=localhost;dbname=test;','user','pass');

$var='user_test';
$sql=$dbh->prepare("SELECT user FROM users WHERE user = :test");
$sql->bindValue(':test', $var, PDO::PARAM_STR);
$sql->execute();

$sql->debugQuery();
print_r($sql->debugBindedVariables());

Resulting in

SELECT user FROM users WHERE user = 'user_test'

Array ( [:test] => user_test )