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Although the EARLIER function in DAX is complicated, it's also very useful! This blog shows how the function works, and how to use it to create running totals, sort rows, create group statistics and divide data into bands.
- The EARLIER function in DAX
- Running totals using the EARLIER function in DAX (this blog)
- Using the EARLIER function to rank data
- Group statistics using the EARLIER function
- Banding using the EARLIER function
Posted by Andy Brown on 13 January 2016
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Running totals using the EARLIER function in DAX
To get this example to work, first bring the PosDate column from the Pos table into the Transaction table:
Use the RELATED function to bring the point-of-sale date for each transaction into the transactions table.
The answer we're aiming for
When travelling, it helps to keep the destination in sight. Here's what we want to achieve:
We'll create a new column giving the cumulative quantity (although this makes more sense if you sort the transactions by date, as below).
If you sort the transactions into date order, the figures make more sense:
Because the database doesn't record the time of the transaction, figures for each day's sales are lumped together.
The formula to achieve this
Here's a formula which would achieve this:
'Transaction'[PosDate] <= EARLIER ( 'Transaction'[PosDate] )
That is, instead of summing the quantity for the current row's transaction, sum it instead across the set of those rows whose transactions take place on a date up to and including the transaction date for the current row.
Don't forget (I often do) that this has to be the formula for a calculated column, and not a measure. Because it's referring to the value of the PosDate for the current row, a measure would make no sense and would return an error.
Next up - ranking using EARLIER.