Chapter 9 Building the Shopping cart

1. Chapter 9Building the Shopping cart • Objective • Creating Shopping cart using session Variable. • Creating a shopping cart using a database table. • Use the native methods of the ADO to add, delete & update records in a recordset.

2. Using session Variable to create a Shopping cart • Every products selected by the customer is add to a cart called shopping cart. • One way to create shopping cart is by assigning an array to session variable. • New items can be added o a shopping cart or existing items can be removed. • This isn’t the best method of creating shopping cart bcoz the shopping cart relies on session variables & sessions variables are notoriously unreliable.

3. Contd… • When the visitor first arrives at a Web site that uses Session variables, the Web Server adds a cookie to the visitor’s browser that tracks the visitor as he moves from page to page. • When the session variable is created, this cookie is used to associate the variable with the proper user. • If, for whatever reason, the cookie cannot be created on the user’s browsers, the session variables won’t work

4. Reasons that prevent cookie from being added to a user’s browser. • Some older browser simply don’t support cookies. • The recent browsers provide an option to accept or refuse cookies. • The user’s cookie file may be corrupted. • They time out after a preset period o time [default 20 min]. • Advantage is you need not force the customer to register or log in before adding items to a shopping cart.

5. Using Database table to create a shopping cart • First create a table.. • Let us create a table named cart and the following is the schema: • Cart_id • Cart_userid • Cart_productid • Cart_quantity

6. Contd… • As the user selects the product the registration form /log in form is displayed to accept the user’s details along with credit card details. • Every product selected is added to the table just created. • Shopping cart created here is permanent. • Doesn’t rely on the properties of a user’s browser. • Not a single cookie is used.

7. Native ADO Methods • This is the second method of using the ADO o work with a database. • Native methods of ADO are used to modify database records instead of using the ADO to pass SQL strings to a database. • There is no need of alternative method but in certain situations it is more convenient. • Multiple records in a database table can be updated easily using native methods of ADO.

8. Creating Updateable Recordset • To modify the records in the Recordset, you must open the Recordset in such a way that it is updateable. • By default the Recordset is read only. • You can open a modifiable Recordset by changing the Recordset’s LockType property. • Statement to open record set: • RS.LockType=adOpenOptimistic • Results in the least interference with other users and is least likely to cause database deadlock.

9. LockType Property values • adLockReadOnly • adLockPessimistic • adLockOptimistic • adLockBatchOptimistic