topic Re: nested for loop in QlikView

nested for loop

surajap123 — Wed, 25 Nov 2020 16:16:04 GMT

Hi Experts,

I know how the for loop works. I use it to load multiple tables, to create all variables in QlikView present in excel file.

I wonder how the nested for loop works. I see the code looks like below-

for i =1 to 10

//code

for i =1 to 10

//code

I have seen various examples in the community, but find it difficult to understand the code.

-Which for loop runs first?

-How many max nestings we can do?

-Could anyone explain me simple examples or some use cases where we can use nested for loop?

Thanks

Re: nested for loop

maxgro — Sun, 21 Aug 2016 17:12:56 GMT

Could anyone explain me simple examples or some use cases where we can use nested for loop?

you can try to see the result adding a trace to the loop, example (nested loop to generate odd month start date

for year = 2015 to 2016

for month = 1 to 12 step 2

trace year=$(year) month=$(month);

😧

load makedate($(year), $(month)) as OddMonthStart

AutoGenerate 1;

next month

next year

Which for loop runs first?

in my example

year 2015

month 1 3 5 7 9 11

year 2016

month 1 3 5 7 9 11

How many max nestings we can do?

I don't know but I never used more than 2 nested loop

Re: nested for loop

ecolomer — Sun, 21 Aug 2016 17:14:57 GMT

In your example you have two loops but both have the same index i.

You need two diferent index

for i =1 to 10

//code for i

for k =1 to 10

//code for k off each i

The sequence are:

i=1

//code for i=1

k=1

//code for k=1 and i=1

k=2

//code for k=2 and i=1

...

k=10

//code for k=10 and i=1

i=2

//code for i=2

k=1

//code for k=1 and i=2

k=2

//code for k=2 and i=2

...

k=10

//code for k=10 and i=2

...

Re: nested for loop

surajap123 — Sun, 21 Aug 2016 17:29:12 GMT

Thanks for the replies.

I am now getting idea how it works.

Personally I have issues identifying the correct tool( say nested for loop) to fulfill a particular requirement.

Could you list out few common requirements which nested for loop can fulfill, which cannot be achieved by normal for loop?