Aggregation in QlikView is usually done in the UI. There is a SUM() aggregation function that can be used in Text Boxes (to sum exeverything selected) or in an Excel Worksheet-like object like a Straight Table.
Internal tables can be viewed as Excel Worksheets. They contain rows and columns. Load your data as-is, and aggregate in the User Interfac, just like in Excel.
For example, if your field in the above example data is called... Example, load the data as-is and create a text box. In the expression field, type =Sum(Example).
If you want to aggregate in the Load script, you won't be able to un-aggregate again later on. To sum values in your load script, use the GROUP BY clause and again a Sum() function to sum column values from different rows.
In excel you have to mention the range to sum up.
Here you have to just add the name of Column ,QlikView automatically sum all the records present in that field. These can be less in number or can be in millions..
For this use script :
from abc.xls ] ;
Let Field2 is the name of Column which you want to sum, then use expression