Detailed explanation of PHP access to Oracle stored procedure instance

create or replace package PKG_TRANS_REL is
 
 -- Author : test
 -- Created :
 -- Purpose : test
 
 -- Public type declarations
 PKG_NAME varchar2(20) := 'PKG_TRANS_REL';
 --存储过程，测试用
 procedure pro_GC_withdraw(in_merch_no   in varchar2,
              in_withdraw_amt in number,
              out_result   out number,
              out_errmsg   out varchar2);
end PKG_TRANS_REL;

$this->_pdo = new PDO(PDO_DB_DNS, PDO_DB_USER, PDO_DB_PASSWORD);
$call = "CALL PKG_TRANS_REL.pro_GC_withdraw(?,?,?,?)";
 
try{
    $stmt = $this->_pdo->prepare($call);
 
    $stmt->bindParam(1, $merch_no);
    $stmt->bindParam(2, $amount, PDO::PARAM_INT);
 
    $stmt->bindParam(3, $result, PDO::PARAM_INT, 4);
    $stmt->bindParam(4, $error_msg, PDO::PARAM_STR, 64);
 
    $stmt->execute();
 
  }catch (PDOException $e)
  {
    $msg = 'SQL:'.$e->getMessage();
    $msg = iconv('GBK','UTF-8',$msg);
    user_dump('SQL:'.$msg);
    return false;
  }
 
  ...