Just like Oscar stated, it is generally considered a best practice to have database primary keys that have no business meaning attached to them. The example you provide appears as though it probably should be defined as a unique not null column, but not primary key. But even if you change the data structure that doesn't solve the problem of auto assigning the "next" value to a new record.
The method I have used in the past for situations like this to have a table in the database that holds the "next" value. Then update the value database either in a transaction from your application, or in a stored procedure used to save a new record, or with a trigger on the insert statement. Hope that helps, Nathan On Sun, Dec 14, 2008 at 8:51 PM, sudhakargupta < [email protected]> wrote: > > Thanks for your reply and i need an id likes the 05-CS-123 so, i need an > auto > generated string to increment the last number, if the client want to use > the > assigned then how to mention in model class to assign the @Id value. > > > Sudhakar > > > Oscar Alvarez-2 wrote: > > > > Hello, > > > > What's the diference between autogenerated Long key and autogenerated > > String > > key???, i mean, if the String is autogenerated, it's not better solution > a > > Long key?, but if the String key is meaningful for the end user, then you > > should define assigned strategy and assign it before save. > > > > Best Regards > > > > > > > > 2008/12/13 sudhakargupta <[email protected]> > > > >> > >> Thanks for your reply > >> > >> Is there any other way to use the auto generator for the string in > mysql > >> or in any other database > >> > >> please suggest me for this solution.. > >> > >> Sudhakar.. > >> > >> > >> > >> mraible wrote: > >> > > >> > If you're going to use Strings for the primary key, you'll have to use > >> > a type of generator that doesn't increment. I've never done this, > >> > hopefully someone else on this list can help you. > >> > > >> > Matt > >> > > >> > On Fri, Dec 12, 2008 at 5:39 AM, sudhakargupta > >> > <[email protected]> wrote: > >> >> > >> >> Hi Matt... > >> >> > >> >> > >> >> Presently i'm working with the appfuse2 struts.. In one of my table > i > >> >> need > >> >> to use the String as a primarykey and use foreignkey relations with > >> this > >> >> primarykey. > >> >> > >> >> i created a model class primary key setters/getters are > >> >> > >> >> > >> >> @Id > >> >> private String code; > >> >> > >> >> private String getCode() { > >> >> return this.code; > >> >> } > >> >> > >> >> private void setCode(String code) { > >> >> this.code = code; > >> >> } > >> >> > >> >> and after that run the command like mvn appfuse:gen and creates the > >> all > >> >> the > >> >> action classes and the jsp files. after that run the command like mvn > >> >> jetty:run, then it shows the errors to create the database and to run > >> the > >> >> project.. > >> >> > >> >> it shows the errors like primarykey field must be the Long > datatype.. > >> >> > >> >> can u please suggest me to create the database through appfuse .. > >> >> > >> >> > >> >> Sudhakar > >> >> > >> >> > >> >> > >> >> > >> >> -- > >> >> View this message in context: > >> >> > >> > http://www.nabble.com/Appfuse2-Struts-problem-tp20974893s2369p20974893.html > >> >> Sent from the AppFuse - User mailing list archive at Nabble.com. > >> >> > >> >> > >> >> --------------------------------------------------------------------- > >> >> To unsubscribe, e-mail: [email protected] > >> >> For additional commands, e-mail: [email protected] > >> >> > >> >> > >> > > >> > --------------------------------------------------------------------- > >> > To unsubscribe, e-mail: [email protected] > >> > For additional commands, e-mail: [email protected] > >> > > >> > > >> > > >> > >> -- > >> View this message in context: > >> > http://www.nabble.com/Appfuse2-Struts-problem-tp20974893s2369p20988292.html > >> Sent from the AppFuse - User mailing list archive at Nabble.com. > >> > >> > >> --------------------------------------------------------------------- > >> To unsubscribe, e-mail: [email protected] > >> For additional commands, e-mail: [email protected] > >> > >> > > > > > > -- > > Atentamente > > Oscar Alvarez V > > (09) 8416 4052 > > > > > > -- > View this message in context: > http://www.nabble.com/Appfuse2-Struts-problem-tp20974893s2369p21008315.html > Sent from the AppFuse - User mailing list archive at Nabble.com. > > > --------------------------------------------------------------------- > To unsubscribe, e-mail: [email protected] > For additional commands, e-mail: [email protected] > >
