Re: duplicate entry for key

[Todd Farmer]

Hi abhi,

abhi mahajan Wrote:
-------------------------------------------------------
> 'uname' is set as unique
...
> 1. after filling the entries in java application
> and after successful entry in table, i get an
> exception message after closing application as:
> "exception occurs : duplicate entry 'lambda' for
> key 2"
> this whole entry is successfully inserted into
> table. so what is the meaning of 'duplicate entry'
> nd why is it happening??

Because there were two INSERT statements with a "uname" column value of "lambda". Enable the general query log if you need to see the commands actually received by the server.

> 2. suppose i inserted a row in table through
> application, after successful entry in table i get
> an new eid as 106 (say), means that last entry of
> table had eid content as 105. nw if i delete this
> account i.e. with eid as 106 and then re-enter new
> values in table, i get the new eid as 107 instead
> of 106 which ws deleted previously. why is this
> happening nd what could be done to avoid this??

You don't want to do this, really. MySQL won't recover and reuse auto-increment values after rows have been DELETEd. You could, conceivably, issue ALTER TABLE statements to reset the auto-increment counter, but just don't do it. Take a long hard look at why your application needs to do this.