Create For Loop in PL/SQL

Hi Guys,

I will highly appreciate your help in advance!
I'm new using PL/SQL codes, but I really need to get this done in PL/SQL, because of the massive data I'm working with. I need to get the Top 100 percentage of Sales, and I'd like to know if I could declare a variable in PL/SQL so I can run different queries using the For Loop. I was using Access to get the Top 100 percent of Sales and I was able to declare a variable to be use in the For loop. Lets say I want to run the TOP 1 Percent from TabelName, then Top 2 Percent from the same table, then Top 3 Percent from the same table and so on...
Here is the VBA code I'm using;

Dim X as integer


For X = 1 To 100
           
            DoCmd.RunSQL "DELETE Table1.* FROM Table1;"
            DoCmd.RunSQL "INSERT INTO Table1 SELECT TOP " & X & " PERCENT *" & _
            "FROM CustSales;"
            INSERT INTO Table2 ( CustNo, Sales )
SELECT Count(Table1.CustNo) AS Tot_Members, Sum(Table1.SALES) AS TotalSales
FROM Table1;

Next X

Basically I clean Table1 then I insert the Top 1 Percent Customers and sales from Table CustSales then I get the summary from CustSales table and inserted into Table2 to add up all my results from Table1 (1 to 100 percent). CustSales table holds about 2,500,000 records; this is the reason why I need to get this done in PL/SQL.

Thanks so much for your help!