On 01/11/10 18:38, Jonathan Tripathy wrote:
>
>>> Hi Andy,
>>>
>>> Thanks for your reply. Would the above code be classed as a single
>>> transaction then?
>> Yes, assuming there's no explicit transaction control
>> (COMMIT/ROLLBACK/END) in your queries.
> Actually, we do have maybe one or 2 queries that use ROLLBACK, however
> ROLLBACK happens at the end of a "code block" so the question is
> probably moot.
Please ignore this above comment from me. We are using JDBC's rollback()
method, instead of comitt() (in a catch block), so all seems fine.
>>> And if so, I could just simple leave out the line which
>>> says "//Insert SQL here to lock table"?
>> In PostgreSQL, locking is done automatically depending on actual
>> isolation level and SQL queries.
>> You can use explicit locking but most of the time it's not needed.
>>
> I'll give you the exact case where I'm worried:
>
> We have a table of customers, and each customer can have multiple
> memberships (which are stored in the memberships table). We want our
> deleteMembership(int membershipID) method to remove the membership,
> then check to see if there are no more memberships left for the
> corresponding customer, and if there are none, delete the
> corresponding customer as well.
>