Question

Example i have this table

table transaction

• id int (PK)
• unit varchar(10)
• journal_number

journal number is combination of unit and a sequence. so example data could be like this

id | unit    | journal_number
------------------------------
1  | 'unit1' | 1
2  | 'unit1' | 2
3  | 'unit2' | 1
4  | 'unit2' | 2

...

i how to create the journal_number automatically ?

is there any solution for this in hibernate without doing this manually ?
like using a Generator

If i have to do this manually, for example if there is a new row for the ‘unit1’. then i have to to this

select max(journal_number) where unit = 'unit1'

then asign the result to the new row

Answer 1

I don’t Know if I got your point.But it seems that yo want a composite Key.
if yes then there is way that you can do in your mapping file.

<composite-id name="MyKey" class="string">
  <key-property name="firstKey"/> 
  <key-property name="secondKey"/>
</composite-id>