Most application forms do not interact solely with a single table directly but instead select, insert, update, and delete data from multiple tables. Because multiple statements may need to be executed, the use of transactions is necessary to ensure atomicity, consistency, isolation, and durability. These four characteristics are also known as the ACID properties:
The atomic property helps ensure that a transaction is fully complete or not started at all. If there is an error, the database should revert any changes to the start of the transaction.
A transaction also helps to enforce consistency in the system state, meaning that the system should always be in a valid state.
A transaction should run in isolation, meaning that it should be the only action that should be running on the system at one time. If two (or more) transactions are performing the same function simultaneously, the transaction isolation will ensure that each transaction thinks it should have exclusive use and lock on the database rows that the transaction affects.
The durability of the transaction means that once the transaction has completed successfully, all of the changes should be permanent.
In this assignment, you will create the functionality in your CapestraApp project to create new orders. The customer for whom the order is being placed is selected from a drop-down list of all current customers. The product is selected from a drop-down list displaying all current products. Once the customer and product have been selected, the user should enter the desired quantity to be ordered. Once all of the fields have been inputted, the user can then click the Place Order button, which will call a new method called placeOrder(). This method should check to see that all fields have been filled, and it should display an error if this is not the case. Then, placeOrder() should call a similarly named method in the database interface that attempts to place the order.
RESOURCES
Place Order Functionality: To-Do List [DOCX].
Capestra Furniture SRS [DOCX].
Implementing place order functionality, part 1. | Transcript
Implementing place order functionality, part 2. | Transcript
Implementing place order functionality, part 3. | Transcript
Implementing place order functionality, part 4. | Transcript
Sample Solution