File comapre and merge

I have two excel files. I want to compare two files and merge.

data in these files are exported from a DB.

File1 has data like this in two columns

primary-key | description
--------------------------
1| hello
2| zero
8| erwd



File2 has data like this in two columns

primary-key | description
--------------------------
1| hello
2| zero
3| mnp



I want to make File3 merging these two files like this.

primary-key | description
--------------------------
1| hello
2| zero
3| mnp
8| erd



How can I do this in excel ?