Same Connection for two PreparedStatements?

Question

Dear Experts,
Is it better to use two connections for two different PreparedStatements ?
Let me elaborate:
I have to iterate in a loop & for each iteration I need to
a) Select a row.
b) Possibly update that row depending on some condition.
My question is:
Do I use only one connection, & then use the select & update (one after the other) on the same connection,
Or do I use two different connections & have two separate preparedStatements & just execute them each time in the loop?
Thank you for your anticipated responses.
Sandeep

Answer 1

Here is how I would approach this issue:
In the database table, I would add another column called 'version'. When the record is first inserted into the database, I would set version=1. Each time the record is updated, I would increament version by 1 (example: 2, 3, 4, etc).
Now, in your program, I would open a conneciton, then I would read in all the records at once (via a query) into an array. I would not read in all the fields from each record, just read in the fields you need to examine, plus read in the 'version' field. Close the resultSet and preparedStatement since you dont need them anymore for the query because you transfered all the data into the array.
Next, I would use the same connection to create a new preparedStatement for updating. Loop through the array looking for a record you need to update. If you find one, I would update the record but add to the sql's 'where' clause a test to ensure the record has not been altered since the last time it was updated (check the 'version'). Example:
update person set firstName='Joe', version=(23+1) where verson =23.
Where '23' came from the 'version' you stored in the array you previously read in. If the update returns with a '1', it
was updated successfully. If it returns '0', the record was updated while you were evaluating the record. If that happens, take whatever action you think you need to take. Note there is no need to set up a transaction.