Copy missing rows from one table to another in sql server with stored procedure

Question

I have to tables in different databases (on the same server) that are identical. I need to transfer the data rows from the left database table to the right database table, but I only want to transfer the rows that aren't in the right database table already.

Is there a neat way of doing this?

Im using SQL Server 2008 R2

Answer 1

Assuming that you can uniquelly identify a row with column id:

insert into databasename..tablename
select * from datababasename2..tablename2
where id not in (select id from databasename..tablename)