If I understood well, you want to avoid duplicates, this is if No Key exists in Table X, you do not want to load the same No from Table Y. If this is the case, you can first load Table X and then use the WHERE NOT EXISTS(No) while loading Table Y.
delete left join and Table Naming T2:, then it should work. also ensure that the field No is not loaded before in the script with exception in T1. If No is loaded somewhere else before in script not exists checks every previously loaded value, not only values of t1.