transfer data from one id to another



Hello, 

We have one employee with two id's. Now we want to delete one id, but we still need to transfer their data from one id to another to keep records up to date. The id which we want to delete it depends on 26 tables. How could I transfer all data from that table? Is there any way to transfer automatically? Could you please share some ideas with me? Another word, I can say I want to merge two id's data, and then I want to delete another id.