Newbie Needs Help Writing Query

OK, I have two tables that have pretty much the same data in them, but, the first table has SOME data that the second table doesn't and I need to get that data into the table that does not have it.

Here's a description of what I want to do:

Table #1 has about 10,000 lines of data with the employee SSN as the ID for the records. In this table are two extra columns of data (HRContact)and(HR ContactCode) that are not always populated in Table #2.

Table #2 has about 300,000 lines of data with the SSN as the ID field. Some of the records that match the SSN's from Table #1 have the data HRContact and HRContactCode, but not all of the records have those fields populated.

So, what I need to happen is for the query to go through Table #1, find the SSN of a record. As it finds each SSN, it goes to Table #2, finds that same record with the same SSN, then looks in the HRContact field to see if there is data there, or if it is Null. If there is data in that field, then it goes on to the next SSN in Table #1 and repeats the preceeding process. If the data in HRContact is Null in Table #2, then it goes back to Table #1 and grabs the HRContact and HRContactCode data for that record and writes it into the HRContact and HRContactCode field for the record in Table #2. the query would repeat this process until it reaches the end of file in Table #1.

I hope this is clear and if you have any questions, please ask me...

Thanks for your help,
Dave