# Choosing first and last month in BM

Coach

Is there a way to use fixed functions or something else to grab the first date that appears and the last date that appears?

I am trying to calculate yearly attrition. I have it by month but adding up or avg the monthly % is not mathematically correct. I need to get the first month and last month's values within a certain timeframe. I did do some hard-coded stuff in ETLs but people want to be able to choose the timeframe and other filters in order to calculate a yearly value.

Essentially I have what is below. I want to grab min month value1 and max month value 1 and add them together. After that, I would want to add up everything from value2 and then divide that by the sum of the min + max date of value 1.

Start Date End Date Value1 Value 2

1/1/22 1/31/22 500 2

2/1/22 2/28/22 510 8

3/1/22 3/31/22 505 3

4/1/22 4/30/22 507 1

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• Coach

Earliest date for the year

```MIN(MIN(`Date`)) OVER (PARTITION BY YEAR(`Date`))
```

Latest date for the year

```MAX(MAX(`Date`)) OVER (PARTITION BY YEAR(`Date`))
```

Remove the partition clause if you want it across your entire dataset.

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• Coach

Earliest date for the year

```MIN(MIN(`Date`)) OVER (PARTITION BY YEAR(`Date`))
```

Latest date for the year

```MAX(MAX(`Date`)) OVER (PARTITION BY YEAR(`Date`))
```

Remove the partition clause if you want it across your entire dataset.

**Did this solve your problem? Accept it as a solution!**
• Coach

Thank you @GrantSmith exactly what I needed!

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• Coach

@GrantSmith so I am able to use those calculations separately but when I try to add them together in the same BM it does the weird blank error thing.

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• Coach

You're getting a blank because your CASE statement is likely returning a NULL value. Are you displaying you data split by anything other than Company?