I have a problem to ask for your help, my friend.
like this table,
If this row and the previous row are the same salesperson, calculate the current and previous day's growth rate, if this row and the previous row are not the same, return null.
How do I write this function? Use the DAX function.
I'm sorry that my English is very poor, so I can only describe it through translation tools.
Thank you for your answer.
| Salesman | Day | Sales volume | Day of growth |
| Bill | 2021/1/1 | 536 | |
| Bill | 2021/1/2 | 874 | 63.06% |
| Bill | 2021/1/3 | 797 | -8.81% |
| Bill | 2021/1/4 | 606 | -23.96% |
| Bill | 2021/1/5 | 784 | 29.37% |
| Bill | 2021/1/6 | 675 | -13.90% |
| Bill | 2021/1/7 | 714 | 5.78% |
| Bill | 2021/1/8 | 730 | 2.24% |
| John | 2021/1/1 | 775 | |
| John | 2021/1/2 | 519 | -33.03% |
| John | 2021/1/3 | 794 | 52.99% |
| John | 2021/1/4 | 958 | 20.65% |
| John | 2021/1/5 | 548 | -42.80% |
| John | 2021/1/6 | 944 | 72.26% |
| John | 2021/1/7 | 655 | -30.61% |
| John | 2021/1/8 | 656 | 0.15% |
| Bob | 2021/1/1 | 867 | |
| Bob | 2021/1/2 | 523 | -39.68% |
| Bob | 2021/1/3 | 734 | 40.34% |
| Bob | 2021/1/4 | 906 | 23.43% |
| Bob | 2021/1/5 | 567 | -37.42% |
| Bob | 2021/1/6 | 906 | 59.79% |
| Bob | 2021/1/7 | 851 | -6.07% |
| Bob | 2021/1/8 | 503 | -40.89% |
