Here you go. I added a date. This script wouldn't delete records off the QVD based on your Excel file changes.
It's just not built to do that. If you're losing records there is something else going on. Like it's not finding your QVD to begin with so it's doing a full reload. When it does a full reload it will create the QVD with whatever is in the Excel file.
So you'll probably want to step through it and make sure the IF statement I put in is 'catching'.
//Check if QVD exists; if not do full reload
if isnull(QvdCreateTime(EMP.qvd)) THEN
EMP:
LOAD [EMP ID],
[EMP NAME],
Designation,
Department,
Today() as ImportDate
FROM
Book1.xlsx
(ooxml, embedded labels, table is Sheet1);
Store EMP into EMP.qvd;
Drop Table EMP; //Drop the initial load table after storing QVD
//if QVD does exists only add new records
ELSE
EMP:
LOAD [EMP ID],
[EMP NAME],
Designation,
Department,
ImportDate
FROM
EMP.qvd
(qvd);
Concatenate(EMP)
//Loading new base file into temp table
EMP_Temp1:
LOAD
[EMP ID],
[EMP NAME],
Designation,
Department,
Today() as ImportDate
FROM
Book1.xlsx
(ooxml, embedded labels, table is Sheet1)
where not exists([EMP ID]);
Store EMP into EMP.qvd;
Drop Table EMP;
ENDIF;
Let vEMPRecordsQVD = QvdNoOfRecords('EMP.qvd');//Fetch no of records from initial base QVD
