I'm using sql and have data coming from redshift. The data is cumulative, so It keeps adding the previous total and the new total which is why the graph is linear. I want to subtract each row by the...

I'm using sql and have data coming from redshift. The data is cumulative, so It keeps adding the previous total and the new total which is why the graph is linear. I want to subtract each row by the previous row in order to get the monthly values instead of cumulative value. For example, for 8-2022 the value should be 13 million instead of 34.7. So I would want the 8-2022 column to subtract from the 7-22 column to get the correct value.