topic how do I use exists() in if.then.else expression? in QlikView

how do I use exists() in if.then.else expression?

Tue, 09 Jun 2015 10:40:11 GMT

I want to conditionally load data based on whether a specific value has already been loaded.

In a Where clause I would use: where exists(fieldname, 'value')

But I want to do

IF exists(fieldname,'value')

THEN

LOAD ...

ENDIF

Re: how do I use exists() in if.then.else expression?

alexandros17 — Tue, 09 Jun 2015 15:16:59 GMT

exists must be used in a Load instruction because it check every row, to execute your condition you shoul have to load the table with a where condition on that value, then if there are rows (so the value exists) you can do the following Load

Hope I've been clear

Re: how do I use exists() in if.then.else expression?

Tue, 09 Jun 2015 15:22:10 GMT

Seems a complicated method. Is there a succinct way to phrase it? Ideally I want to set a variable on the existence or not of the value.

Re: how do I use exists() in if.then.else expression?

alexandros17 — Tue, 09 Jun 2015 15:24:25 GMT

You're right but you know if a field has a certain value only when you load it and the quickest way is to load the table for that value ... I think there are not other options

Re: how do I use exists() in if.then.else expression?

jmmayoral3 — Tue, 09 Jun 2015 15:24:47 GMT

If you want to load only rows when the condition was true, you don´t have to use

IF exists(fieldname,'value')

THEN

LOAD ...

ENDIF

You have to use

LOAD .....

FROM (OR RESIDENT....)

WHERE fieldname='value';

Re: how do I use exists() in if.then.else expression?

Tue, 09 Jun 2015 15:33:19 GMT

Thanks, Alessandro. I am still learning which logic is applicable where!

Re: how do I use exists() in if.then.else expression?

marleygt — Tue, 09 Jun 2015 15:42:56 GMT

Hi Peter!

I met a similar situation on my last job, where I need to load for several customers with different data (especially in area code and sales agents) and I solved this way:

I set a couple of Variables - generic - and then I just use IF condition for uploading.

IF(vSetProvince=P) THEN

TableFact:

LOAD data1,

data2,

data3,

...

FROM

[File Qvd\FactsTable1.qvd]

(qvd);

ELSE

TableFact2:

LOAD data1,

data2,

data3,

...

FROM

[File Qvd\FactsTable2.qvd]

(qvd);

ENDIF

Hope this could help!

Alex