Lab week 10 Aggregates and sub-queries And assignment details

Use North wind

1 Building joined queries Select the product name and the company name of the supplier for each product. Select the supplier name, the product name and the order Id for each order detail. (Note the number of rows) Select the supplier name, the product name, the order id and the customer’s company name. Omit the order id and the product Id from the previous query and add the word ‘distinct’ after the select clause.

2 Using sub queries to negate The last query on the previous slide shows us all the suppliers and the customers to which they supply. List all the suppliers who supply to the company named ‘Chop-suey Chinese’ –How many joins do you need? Using a sub-query, list all the suppliers who DON’T supply to the company named ‘Chop- suey Chinese’ –Do you need as many joins in the sub-query? –Can you make the query any shorter than it is now?

Queries How many shippers are there in the Northwind database that have never shipped any orders? List the name of each customer’s company and the total amount they have spent with us, in descending amount spent order. List the name of each customer’s company and the total amount they have spent with us, for all companies that have spent more than the average amount with us.

More queries List all orders that have more than the average number of order details. List sum of the cost of all order details, summed over the product id and over the orderid.

Assignment details Look up the case study that you were given in Software Engineering. Design an Entity Relationship diagram to hold all of the data required for your system. This assignment is due in on Tuesday, 13 th December Use ERWin to document your tables.

ERWin Program files > CA Associates > AllFusion > ERWin Data Modeler > ERWin

Starting ERWin

Pick your model type…

Blank model

To add… Entities –Right click on the entity icon in the browser The browser is the left panel on the screen

To add attributes… Expand the entity icon. Right click on the attributes icon and add an attribute. Right click on the attribute, to open the properties. –Here, primary keys can be set and data types can be allocated.

Adding foreign keys

How to Open the ‘parent relationship’ from the course. Choose the student as child entity. –Note, if you tick ‘identifying’, the key will become part of the primary key of the child entity.

Result of ‘identifying’

Non-identifying…

To get ‘physical’… Drop down the ‘logical’ box to get ‘physical’.