topic Empty Multiple QVDs in QlikView

Empty Multiple QVDs

microwin88x — Wed, 25 Nov 2020 16:16:04 GMT

Hello,

I have a folder with the following files:

General_Accounts_1.qvd

General_Accounts_2.qvd

Specific_Accounts_3.qvd

Specific_Accounts_4.qvd

Summary.qvd

Work.qvd

What I need is to empty all files in bold (Starting with General_Accounts_* and Specific_Accounts_*) by script.

I need to do that to initialize the files with 0 kb because then I have to run a process that stores the data I need.

Do you know how to do that? (Please, I don't need macros or CMD commands)

Thank you!!!

Re: Empty Multiple QVDs

maxgro — Sun, 07 Aug 2016 20:33:13 GMT

look at the last approach here

QlikTip #30: How to delete existing QVD files via load-script

Re: Empty Multiple QVDs

trdandamudi — Sun, 07 Aug 2016 20:34:37 GMT

I am not sure if I understand your question. When you run the process the qvd will get over written automatically.

So for example when you run the script for the first time a file General_Accounts_1.qvd is generated. When you run the script second time, the existing qvd file General_Accounts_1.qvd is over written.

Hope this helps. If not can you please be little specific.

Re: Empty Multiple QVDs

microwin88x — Sun, 07 Aug 2016 20:46:18 GMT

Yes, the problem is that I have a process where I generate multiple QVDs, for example: General_Accounts_1, General_Accounts_2, General_Accounts_3, etcetera. And it can change from time to time. The first run I could get 5 files, the second run maybe one only 3. So I need to make sure to delete the content from all because I don't want to read data from a previous run (because then I use LOAD FROM General_Accounts_* and if I do that on the second run I'd be reading data from files 4 and 5). If I empty all at the beginning I make sure I read only the needed data...

Re: Empty Multiple QVDs

microwin88x — Sun, 07 Aug 2016 21:01:17 GMT

I can't get it to work on my script I get an error on line 62: WHERE Exists(Dim1)

Re: Empty Multiple QVDs

maxgro — Sun, 07 Aug 2016 21:34:33 GMT

see the attachement

I changed 1 line in the sub

WHERE 0=1 //Exists(Dim1)

Re: Empty Multiple QVDs

trdandamudi — Sun, 07 Aug 2016 21:45:36 GMT

Ok got it. Give a try on the below code. I am also attaching a sample app for you to play around.

What this app does is:

1) First it will empty all the QVD's in a sub folder

2) Then it creates two QVDs in the sub folder.

Hope this helps....

SUB EmptyQVDFiles (Path)

//Check file exists

For each File in Filelist ('$(Path)')

IF (NOT isNull(qvdCreateTime('$(File)'))) THEN

//Check if QVD is already empty

IF (qvdNoOfRecords('$(File)') > 0) THEN

//Load the table structure from the existing QVD

//using Where clause which returns no records

Table_Structure:

LOAD

FROM '$(File)' (qvd)

WHERE 1<>1;

//Store table Structure back into QVD

STORE Table_Structure INTO '$(File)' (qvd);

DROP TABLE Table_Structure;

End If

Next File

End Sub