I am updating large number of records one by one using c sharp. The requirement is such that I have to write sql query in c sharp. Requirement compare records from table 1 with records in table 2 on the basis of Id,if found in table 2 update in table1,not found set message Id does not exists,if got exception update exception message and this I am doing one by one by using foreach loop to compare. But In case of large number of records it takes time for 100000 records it takes 2 Hours,how to use multitasking to make processing faster.