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Power Query: Revision Time – Part 7

22 May 2024

Welcome to our Power Query blog.  Today, I continue to create a refreshable revision timetable by randomising the subject slots I need for the timetable.


As my salespeople take a well-earned break, many students here in the UK are preparing for exams in the summer.  To help my own offspring get organised, I volunteered to create a refreshable printable revision timetable.  This is the result:

I needed a list of topics, and to begin with, I created extra entries for topics that required more timeslots:

We agreed on half-hourly slots, and I created a grid so that my daughter could indicate the slots that she wouldn’t be able to revise. 

When I first designed the solution, I included some Excel functions, but since this is a Power Query blog, I will ensure that I only use Power Query functions (apart from some formatting at the end!).

In Part 1, I converted my data into two [2] Tables: Subjects and Availability.  I extracted Subjects to Power Query.

I created the Availability query by taking a copy of Subjects, and amending it:

In Part 2, and Part 3, I calculated the number of subjects and the number of slots on Availability.

This gave me both totals:

In Part 4, I calculated how many times each subject will appear in a new query, remembering to round up to whole slots.

This told me the number of slots that each subject should have for my example is three [3]:

In Part 5, I created a table where each subject appeared three times (i.e. the number of times given by Subject_Slots).  

In Part 6, I randomised the order of the slots ready to add to the timetable:

I need to take a reference copy of the Availability query, which I will call TimeTable:

I need to unpivot the day data, but as I described in Part 3, unpivoting will not include the data with null values.  These values are vital here, as they are the timeslots I need to fill.  I need to replace null with zero [0] for all the day columns.  I select all the day columns and right-click to choose ‘Replace Values’:

I right-click again and choose to ‘Unpivot Only Selected Columns’:

This gives me all the data in a format that I can use to merge with Random_Subject, but I need to allocate numbers to the slots. 

Next time, I will continue to transform this data by numbering the slots.


Come back next time for more ways to use Power Query!