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

On 01/09/2013 12:27 PM, Rouslan Placella wrote:

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)

And how about another example with non-numerics:

mysql> insert into actor (actor_id, first_name, last_name) values (999,"baraaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa","baz"); Query OK, 1 row affected, 1 warning (0.01 sec)

mysql> show warnings; +---------+------+-------------------------------------------------+ | Level | Code | Message | +---------+------+-------------------------------------------------+ | Warning | 1265 | Data truncated for column 'first_name' at row 1 | +---------+------+-------------------------------------------------+ 1 row in set (0.00 sec)

Bye, Rouslan

...

I'll do this (re checking and return saved value) only for numeric since identified only those. Any objections ?

Regards !

Chanaka Dharmarathna