topic Re: How to retrieve previous values in Talend Studio

How to retrieve previous values

somersst — Fri, 17 Aug 2018 17:41:54 GMT

I've the following table

I want to obtain the following :

So I need something in Talend which I can use to calculate the previous weeks. Above is some simplified, because I need to retrieve the last 10 weeks.

Re: How to retrieve previous values

vboppudi — Fri, 17 Aug 2018 22:55:09 GMT

Hi,

You can try with tMap variables to get your desired output.

Regards,

Re: How to retrieve previous values

somersst — Sat, 18 Aug 2018 06:43:51 GMT

Hi,

can you provide some more information, because it’s not clear to me how to use this tmap. I use it normaly to do ordinary lookups.

Re: How to retrieve previous values

Anonymous — Sat, 18 Aug 2018 07:29:58 GMT

Hi,

A similar issue has been solved by TRF. Could you please refer his post and make suitable changes for your use case?

https://community.talend.com/t5/Design-and-Development/How-to-Perform-Cumulative-in-Talend/td-p/36486

Warm Regards,

Nikhil Thampi

Re: How to retrieve previous values

TRF — Sat, 18 Aug 2018 08:22:34 GMT

You can adapt my post as suggested by @nthampi or go with local tMap variables as proposed by @vboppudi.
The second solution is a little more tricky, what you have to know is that these variables keep their value between rows, so you can "see" values from the previous record.

Re: How to retrieve previous values

somersst — Fri, 24 Aug 2018 15:00:48 GMT

I've found myself a good solution, making use of the tMemorize component.

I included here some screenshots, that should give you a good idea on the solution