How to update alias value again with (if the fields using applymap fucnciton do the mapping before)

[#1]

Hi all, i am new to  Qlikview.

I have some issue as below and hope anyone can provide suggestions to me

Table1:

Class,

Owner ,

Qty,

Table2:

Class,

Owner

1. I create two new fields, Column X and Column Y at table 1 when loading data from Access files
2. Then I update  new fields value by using ApplyMap function
3. Now using field ‘class’ at Table 1 as Criteria (if class="c" or class="e") to update Column X again (conditions: class and Owner between table  1 and table 2 is match before it apply update mechanism)

How can i achieve of it. Many thanks

Mic