How to find difference in similar rows?

JYan01 Registered Posts: 1 ✭✭✭✭
I have a database with a unique ID identifier for each row/record. Rows are created by dates.

For example, say I have 3 rows for borrower #1 for April 1, May 1, and June 1 and their respective rating.

April 1 = A2

May 1 = A1

June 1 = A1

How would I be able to create a column that would identify if the rating has changed from the previous month? So April 1 = no, May 1 = Yes, June 1 = No.

Any help would be appreciated. Thanks.

Best Answer

  • jereze
    jereze Alpha Tester, Dataiker Alumni Posts: 190 ✭✭✭✭✭✭✭✭
    Answer ✓

    If you don't want to code, you have these two recipes that can help you:

    • distinct : to make sure that you have a unique row per month per ID
    • windows : can help with many things, in particular can help you to retrieve the previous value (LAG) in a partition (so you should partition by ID and sort by lonth). To better understand this recipe, have a look at windows functions from the SQL databases.

    I hope that will help.


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