[Phpmyadmin-devel] MySQL data truncation without warning effect to inline edit

Rouslan Placella rouslan at placella.com
Wed Jan 9 13:27:24 CET 2013

On 01/09/2013 05:27 AM, Chanaka Dharmarathna wrote:
> Hi,
>      > > I recently involved in fixing bug [0]. While fixing it, I was bit
>      > confused that, PMA renders user input as it is while inline editing,
>      > without getting real value saved in database. Yes, PMA do this after
>      > checking the result of query execution function. But though result is
>      > not an error, it doesn't mean that data is saved as it was.
>     Mainly this
>      > happens with numeric fields. Just type decimal value for column with
>      > integer type and see what happens after refresh. As mentioned bug
>      > description, MySQL truncate numeric data (not sure about other data
>      > types) without noticing.
>      >
>      > Of course checking again the saved value is cost. But it's really
>     odd to
>      > see a less precise data, represent the real data. I think it's
>     better to
>      > clearly identify the data types, with or without having this
>     behaviour.
>      > So that, we can only recheck needed columns.
>      >
>      > When introducing inline edit functionality, this may have been
>      > discussed. But I think better to discuss again. What do you think ?
>     It sounds quite simple to me, so not sure if I'm missing something here.
>     Anyway, we could just check if any warnings were generated by the query
>     (mysql_warning_count or similar function). If yes, then select the value
>     and send it to the client along with the response. Right?
> Rouslan,
> Yeah, there are functions to detect warnings. But unfortunately this
> kind of queries doesn't throw warnings. As I mentioned MySQL doesn't
> notice about the data truncation.

You absolutely sure? Because to me it looks like MySQL *is* throwing 
warnings. See this:

mysql> use sakila;
Database changed

mysql> insert into actor (actor_id, first_name, last_name)
values ("foo","bar","baz");
Query OK, 1 row affected, 1 warning (0.00 sec)

mysql> insert into actor (actor_id, first_name, last_name)
values (99999999,"bar","baz");
Query OK, 1 row affected, 1 warning (0.00 sec)


> I'll do this (re checking and return saved value) only for numeric since
> identified only those.
> Any objections ?
> Regards !
> --
> Chanaka Dharmarathna

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