topic Re: question about Previous() in QlikView

question about Previous()

Wed, 25 Nov 2020 16:16:04 GMT

Hi,

please, look at my script:

-------------------------------------

load

id,

text,

balance,

Previous(debt)-balance as debt

;

load * inline [

id, text, balance, debt

0, , , 400

1, aaa, 250, 0

2, bbb, 200, 0

3, ccc, 100, 0

];

-------------------------------------------

I expected this:

0, , , -

1, aaa, 250, 150

2, bbb, 200, -50

3, ccc, 100, -150

but, the result is

0, , , -

1, aaa, 250, 150

2, bbb, 200, -200

3, ccc, 100, -100

what's wrong?

thanks in advance!

Re: question about Previous()

kaushiknsolanki — Mon, 13 Feb 2017 09:32:47 GMT

Try this,

Data:

LOAD *,If(Rowno()=1, debt,Peek(Bal)-balance) as Bal;

load * inline [

id, text, balance, debt

0,,, 400

1, aaa, 250, 0

2, bbb, 200, 0

3, ccc, 100, 0

];

Final:

NoConcatenate

Load id,text,balance,debt,if(debt=Bal,0,Bal) as Value Resident Data;

drop Table Data;

Regards,

Kaushik Solanki

Re: question about Previous()

Tue, 14 Feb 2017 07:24:46 GMT

Many thanks, Kaushik!

Works good!

Re: question about Previous()

aveeeeeee7en — Tue, 14 Feb 2017 07:59:00 GMT

Hi Oleg

Do you know why this has happened???

That Previous() function gives you a different Result from Peek() function.

This has happened because of the below Reson:

Previous() operates on the Input to the Load statement,

whereas Peek() operates on the Output of the Load statement.

So, when is it best to use each function?

The previous() and peek() functions could be used when a user needs to show the current value versus the previous value of a field that was loaded from the original file.

The peek() function would be better suited when the user is targeting either a field that has not been previously loaded into the table or if the user needs to target a specific row.

See the detailed description here:

Peek() vs Previous() – When to Use Each

Hope that has given you some conceptual Clarity.

Regards

Av7eN