## Desktop

Highlighted
Regular Visitor
Posts: 22
Registered: ‎07-25-2017

# Calculate days between 2 events in inspection records

Hi Experts

I need to calculate the days between 2 events. It relates vehicles, and inspections are done weekly, but the vehicles are only sometimes serviced. When a vehicle is serviced, i need to calculate the days since it's last service.

My data looks as follows:

Vehicle   Date Inspected    Serviced    Days since previous service

A           date 1                   Y

B           date 2                   N

A           date 3                   N

B           date 4                   N

A           date 5                   Y             date 5 - date 1

B           date 6                  N

A           date 7                  Y              date 7 - date 5

Now the DATEDIFF part is no problem. My problem is knowing how to find the PREVIOUS date serviced, for the vehicle.

My formula for trying to find the previous date currently looks like this:

Prev Service Date =

CALCULATE (

MIN (table [Date Inspected] ),

ALLEXCEPT (Table, Table[Vehicle]),

FILTER (Table, Table[Date Inspected] <= Table[Date Inspected] && Table[Serviced]="Y"))

I do not get an error... but I get the same value for all the rows in the table

Any help will be much appreciated

Accepted Solutions
Super User
Posts: 1,684
Registered: ‎05-10-2016

## Re: Calculate days between 2 events in inspection records

@roelf

Hi, try with this calculated column:

```Days since Prev Service =
VAR DateInspected = Tabla1[Date Inspected]
VAR PreviosDay =
CALCULATE (
MAX ( Tabla1[Date Inspected] ),
FILTER (
Tabla1,
Tabla1[Date Inspected] < DateInspected
&& Tabla1[Vehicle] = EARLIER ( Tabla1[Vehicle] )
&& Tabla1[Serviced] = "Y"
)
)
RETURN
IF ( Tabla1[Serviced] = "Y", DATEDIFF ( PreviosDay, DateInspected, DAY ) )
```

Regards

Victor

Lima - Peru

Proud to be a Datanaut!

All Replies
Super User
Posts: 1,684
Registered: ‎05-10-2016

## Re: Calculate days between 2 events in inspection records

@roelf

Hi, try with this calculated column:

```Days since Prev Service =
VAR DateInspected = Tabla1[Date Inspected]
VAR PreviosDay =
CALCULATE (
MAX ( Tabla1[Date Inspected] ),
FILTER (
Tabla1,
Tabla1[Date Inspected] < DateInspected
&& Tabla1[Vehicle] = EARLIER ( Tabla1[Vehicle] )
&& Tabla1[Serviced] = "Y"
)
)
RETURN
IF ( Tabla1[Serviced] = "Y", DATEDIFF ( PreviosDay, DateInspected, DAY ) )
```

Regards

Victor

Lima - Peru

Proud to be a Datanaut!

Regular Visitor
Posts: 22
Registered: ‎07-25-2017

## Re: Calculate days between 2 events in inspection records

Thanks a lot !!

If you don't mind - won't you explain the use of "earlier" in the formula ?

I do not understand what "earlier" does... I have read somewhere using earlier is quite resource intensive?

Thanks again - works very well

Super User
Posts: 1,684
Registered: ‎05-10-2016

## Re: Calculate days between 2 events in inspection records

@roelf

The EARLIER function take the value of the field before apply the formula context.

You can use a VAR to replace the EARLIER.

Regards

Victor

Lima - Peru

Proud to be a Datanaut!

Regular Visitor
Posts: 22
Registered: ‎07-25-2017

## Re: Calculate days between 2 events in inspection records

Do I understand correctly that you mean do this :

```Days since Prev Service =
VAR DateInspected = Tabla1[Date Inspected]VAR PreviosVeh = Tabla1[Vehicle]
VAR PreviosDay =
CALCULATE (
MAX ( Tabla1[Date Inspected] ),
FILTER (
Tabla1,
Tabla1[Date Inspected] < DateInspected
&& Tabla1[Vehicle] = PreviosVeh )
&& Tabla1[Serviced] = "Y"
)
)
RETURN
IF ( Tabla1[Serviced] = "Y", DATEDIFF ( PreviosDay, DateInspected, DAY ) )```

If I do this - will this use less resource ?

Thanks

Roelf

Super User
Posts: 1,684
Registered: ‎05-10-2016

## Re: Calculate days between 2 events in inspection records

@roelf

Is more legible and understable to EARLIER.

The VAR use less resource when you use it more than 1 time in the DAX Formula.

Lima - Peru