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N1QL Querying for Shoppers and Merchants

· Java Zone

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N1QL is a next generation query language for Couchbase Server. It goes beyond SQL and the relational model in several ways - most importantly, attributes in N1QL can contain multiple values, and these values can be nested. In this blog, we will go over some N1QL queries that are commonly seen in an e-commerce application. This kind of app would have a variety of rich data related to products, customers, and purchases.

First, let's get a list of products belonging to a particular category  (in this case, I am looking for “appliances”)

 SELECT product

 FROM product

 UNNEST product.categoriesascategories

WHERE categories="Appliances"

I’ve now found an appliance that I’m looking to buy, but before I check-out, I need to log into the store. Your app can store user-profiles in Couchbase in the form of JSON documents as shown below :

<span>"resultset": [
     "ccInfo": {
       "cardExpiry": "2013-09-12",
       "cardNumber": "1228-1221-1221-1431",
       "cardType": "discover"
     "customerId": "customer0",
     "dateAdded": "2013-06-23T04:32:31Z",
     "dateLastActive": "2013-07-23T04:32:31Z",
     "emailAddress": "zion@armstronghaley.biz",
     "firstName": "Rosella",
     "lastName": "Tremblay",
     "phoneNumber": "1-543-962-9861 x534",
     "postalCode": "75832",
     "state": "PR",
     "type": "customer"

Now, lets get a list of customers and their e-mail addresses. To do that, you can use the following N1QL query :

SELECT firstName||" "||lastName as fullName, emailAddress

FROM customer

|| is used to concatenate strings in N1QL.  The result of this query will be something like the follows -

<span>"resultset": [
     "emailAddress": "zion@armstronghaley.biz",
     "fullName": "Rosella Tremblay"
     "emailAddress": "kobe@douglas.net",
     "fullName": "Erich Toy"

After I login, I add the item to my shopping cart. Before I check-out, I add a few more items that I like into my shopping cart. I then submit my order. Soon later, the dispatch team is notified that an order is placed and would like to review my purchase order to prepare the package to be mailed out.

The following N1QL query, will prepare the shopping purchase order for “purchase0”

SELECT purchases, product, customer

FROM purchases KEY "purchase0" UNNEST purchases.lineItems AS items

JOIN product KEY items.product

JOIN customer KEY purchases.customerId

Here the document that has purchase information is joined with the product and customer documents to get complete purchase order information.

At the end of the year, the store wants to review its annual sales. The following N1QL query calculates the sales month-over-month.

SELECT substr(purchases.purchasedAt, 0, 7) asmonth, round(sum(product.unitPrice*items.count)/1000000, 3) as revenueMillion

FROM purchasesunnestpurchases.lineItemsasitemsjoinproductkeyitems.product

GROUP BY substr(purchases.purchasedAt, 0, 7)

ORDER BY month

Want more?

We only skimmed over a few N1QL queries related to e-commerce. To learn more about N1QL, check out  http://query.couchbase.com and don’t forget to register for our upcoming N1QL webinar to go over this use-case in more detail.

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Published at DZone with permission of Don Pinto, DZone MVB. See the original article here.

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