Qlikview - Fill with previous value

[qlikviewuser20]

I have a list of many products joined with a date_1 column. I need to add a new field to get the previous date_1 value or the value of the date_1 if there is no previous:

Example:

table source:

Products	Date_1
1638	02/07/2018
1639	01/07/2018
1639	02/07/2018

What i want :

Products	Date_1	Date_2
1638	02/07/2018	02/07/2018
1639	01/07/2018	01/07/2018
1639	02/07/2018	01/07/2018

I used this script :

load
Distinct
Product,
Date_1,
if(product = Previous(product),Previous(Date_1),Date_1) as Date_2
Resident Table_source
order by Product,Date_1 asc;

what i get with my script:

Products	Date_1	Date_2
1638	02/07/2018	-
1639	01/07/2018	-
1639	02/07/2018	01/07/2018

 Any ideas how i can handle that ?

Thanks in advance

[chrismarlow · Accepted solution]

Hi,

Maybe;

load
Distinct
product,
Date_1,
if(product = Previous(product),if(Previous(Date_1)=Null(),Date_1,Previous(Date_1)),Date_1) as Date_2
Resident Table_source
order by product,Date_1 asc;

Cheers,

Chris.

[qlikviewuser20]

It works ! 

thank you very much 😁