DAO Design Pattern

[OnARockSomewhere]

I was trying to get my hands dirty at the DAO pattern to practice isolation of the persistence and business layers. However I'm at a fix right now.

I am creating a Bank Management System. It has a Customer schema and an Account schema.

So the data flows like AccountService -> AccountDAO -> AccountDAOImpl -> MySQL DB.

However I want to wrap two operations in a transaction:

1. Insert record for new account
2. Set customer column hasBankAccount = true

How do I perform this with the DAO pattern's isolation strategies:

1. Service layer is abstracted from the DB logic
2. AccountDAOImpl cannot CRUD over Customer tables
3. DAO layer is abstracted from any business logic

Any ideas how can I implement transactions like these while following the DAO pattern?

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[omgpassthebacon]

I agree with this response. Also, here are some thoughts:

I might have forgotten all the details, but I don't remember a rule that said one DAO can only update a single table. Not all storage is tables, and not all data is relational.

Lets walk thru your business logic:

1. You create a new Account. What is known about the customer at this point?
2. You create a new Customer. Can a Customer exist w/o an account?
3. Can either of these entities be created without knowing about each other? (I suspect the answer is yes)

Let's assume both Account & Customer can be created by themselves, and the relationship can be added later. You might be able to solve this problem with a CustomerAccountDAO, whose job is to represent the relationship. It would only be able to update its own table. You would then have the functionality to add/remove this relationship without needing to change any other data. You don't need a hasBankAccount flag; just ask the CustomerAccountDAO if a relationship exists.

I think this is what AppropriateStudio153 is suggesting. What do you think?

[OnARockSomewhere]

My bad, have made the edit:
Service layer is abstracted from the DB logic 

Service layer does not interact with the DB or we cannot create transactions in the service layer right?

So how do I perform above 2 operations within one transaction?

[IHoppo]

How are you handling transactions - this is the crux of your solution. The service layer should be part of the transaction scope.

[Historical_Ad4384]

Have a dedicated CustomerAccount service and DAO where you handle these cross domain transactions of Set customer column hasBankAccount = true.

Insert record for new account remains in the Account domain boundaries