1) Deos store into qvd overwrites previous qvd or concatenate the new result with it
2) Is it possible that i store the table name and column names and aliases in an excel sheet. Then based on it, the data load script reads the excel sheet and loads the data according to it. If yes, then can you please provide a very simple example below so that i can understand how can i do that
To your first: STORE always replace the old file with the current table you are storing. However, you can always do a load of the existing values, then load the new ones, then store them into the same QVD, so it will keep all files.
FROM Customers.qvd (qvd); // This loads the already existing records in file
CONCATENATE LOAD *; // This will append to the Customers table the following load
SQL SELECT *
STORE Customers INTO Customers.qvd;
To the second, yes, it's possible, although you will need some macro code and loop to load those tables. Check this post to see how that looping may work and if that helps.