Bug #80445 [ReO]: Using float bind parameter returns weird error

Edit report at https://bugs.php.net/bug.php?id=80445&edit=1 ID: 80445 Updated by: cmb@php.net Reported by: domen at jollydeck dot com Summary: Using float bind parameter returns weird error Status: Re-Opened Type: Bug Package: PDO MySQL Operating System: Windows, CentOS PHP Version: 7.4.13 Block user comment: N Private report: N New Comment: Ah, okay, that makes sense. :) Previous Comments: ------------------------------------------------------------------------ [2020-11-30 16:41:12] domen at jollydeck dot com MySQL bug: https://bugs.mysql.com/bug.php?id=101806 ------------------------------------------------------------------------ [2020-11-30 13:33:39] domen at jollydeck dot com Hi, I've stripped the original query of unnecessary stuff so that bug report could be as simple as possible and to avoid wasting your time. Real use case is this: we have a table of "weights" which influence some application logic. After each user action this weight is multiplied by some factor, rounded and limited to lower and upper bound. This could be achieved by retrieving value, doing calculations in PHP and then updating value in table, but "simple" expression GREATEST(LEAST(ROUND(field * ?), ?), ?) does the job and also avoids any table locking that is needed between retrieving and updating the value. I've put word "simple" in quotes because expression has now become GREATEST(LEAST(ROUND(field * CAST(? AS FLOAT)), CAST(? AS UNSIGNED)), CAST(? AS UNSIGNED)) so that is works with stringified numeric bound parameters. I know PDO::PARAM_INT exists, but this is legacy application. ------------------------------------------------------------------------ [2020-11-30 13:13:02] cmb@php.net > $pdo->query("CREATE TABLE test > (field INT NOT NULL) ENGINE=InnoDB"); > $stmt = $pdo->prepare("UPDATE test SET > field = 100 * ?"); This looks plain wrong to me. Why don't you do the calculation in PHP, and send an integer in the first place? And if it is about monetary calculations with floats, you likely have bigger issues than this query[1]. [1] <http://www.floating-point-gui.de/> ------------------------------------------------------------------------ [2020-11-30 07:26:17] requinix@php.net I wouldn't hold my breath on that MySQL bug... Reopening because there is one easy fix we could make that should address the problem: change the error message. Perhaps dropping the data type and just saying "Invalid format". ------------------------------------------------------------------------ [2020-11-30 05:07:57] domen at jollydeck dot com Both workarounds (100.0 * ? and 100 * CAST(? AS FLOAT)) work. Thank you. I will file a MySQL bug report. SQLSTATE code is probably not the appropriate one, if not also the "integer-assuming" behaviour. It looks like MySQL dislikes "numbers as strings" more and more. Last year they've changed behaviour of GREATEST and LEAST functions to treat strings differently. There was no mention of this change in release notes or documentation. See https://bugs.mysql.com/bug.php?id=94267 ------------------------------------------------------------------------ The remainder of the comments for this report are too long. To view the rest of the comments, please view the bug report online at https://bugs.php.net/bug.php?id=80445 -- Edit this bug report at https://bugs.php.net/bug.php?id=80445&edit=1