First you need to add a Data Connection of the Folder type. Once you've created this you can use it to store and read qvd files. In the example below a Data Connection with the name QVData was created first and then used in the load and store statements.
Transactions: LOAD * FROM 'lib://QVdata/salestodate.qvd' (qvd); STORE Transactions INTO 'lib://QVdata/Transactions.qvd' (qvd);
And to store a table named as a variable?
if your table name is a variable, for example: $(TableName) (value is 'MyTable')
Store $(TableName) into 'lib://Qvdata/$(TableName).qvd (qvd);
Doesn´t works. I have a check control on debugging mode and Qlik sense is doing that:
store MyTable into 'lib://Qvdata/$(TableName).qvd (qvd);
and I have a QVD file named $(TableName) and I need that the QVD file is named as MyTable