Get to know the data
Get to know the OVER() clause
Computations with OVER()
Aggregate functions with OVER()
Using OVER() with WHERE
Instruction
That's right! Now, take a look at another interesting example:
SELECT Id, Item, Price, CAST(Price AS NUMERIC) / SUM(Price) OVER() AS Ratio FROM Purchase WHERE DepartmentId = 2;
In the above query, we show all the purchases made by the department where Id = 2.
Note that we divide the item price by the total price of all items purchased by that department. In this way, we can see what part of the total expenditure each purchase constitutes.
Exercise
For all employees where DepartmentId = 3, show their:
FirstName,LastName,Salary,- the difference between their salary and the departmental salary average. Name this column
Difference.
