1. Rob Gleasure R.Gleasure@ucc.ie robgleasure.com
IS6126 Databases for Management Information Systems Lecture 4: SQL IV – Solution
Rob Gleasure
robgleasure.com

2. Exercise
Consider the following problems, what queries best solve them?
We want to select the average Quantity for each ProductID in the OrderDetails table?
SELECT OrderDetails.ProductID,AVG(OrderDetails.Quantity) AS AverageQuantity FROM OrderDetails
GROUP BY OrderDetails.ProductID;
We want to create the same result but with the ProductName from the Products table instead of the ProductID (Hint – use LEFT JOIN)?
SELECT Products.ProductName,AVG(OrderDetails.Quantity) AS AverageQuantity FROM OrderDetails
LEFT JOIN Products
ON Products.ProductID=OrderDetails.ProductID
GROUP BY Products.ProductName;

3. Exercise
We want to create the same result but with the AverageQuantity rounded to two decimal places?
SELECT Products.ProductName,ROUND(AVG(OrderDetails.Quantity),2) AS AverageQuantity FROM OrderDetails
LEFT JOIN Products ON Products.ProductID=OrderDetails.ProductID
GROUP BY Products.ProductName;
We want the same result but displayed according to the first three letters of the ProductName in upper case, e.g.
SELECT UCASE(MID(Products.ProductName,1,3)) AS CompanyAbbrev,
ROUND(AVG(OrderDetails.Quantity),2)
AS AverageQuantity FROM OrderDetails
CompanyAbbrev
AverageQuantity
ALI 
30.09 
ANI 
40