You could always run a query that returns only the different records:
SELECT Trans_Id, number ,Amount FROM myTable1
EXCEPT
SELECT Trans_Id, number ,Amount FROM myTable2
This returns the records that are in myTable1 but not in myTable2
"thanks for your reply, but this i have to do with c# coding."
Then it's a simple merge job:
1) Set up two SqlCommand objects, one per table.
2) Return each table, ordered by the three fields in the same order, into a separate reader.
3) Loop round, building two lists of records that need to be added.
3a) If one side runs out, add all remaining records from the other side to it's list.
3b) If Table1 current record is greater than Table2, add Table 2 record to Table1 list and advance Table 2. Do the same for Table2. If they are the same, move both on.
4) When you run out of records, add the appropriate list to the appropriate table.