There are several methods to perform this particular task,Since all the keys are named I will specify you the fastest and shortest one to do an inner join merge():
A full inner joint as asked in the question can be created using “all” keyword:
A left Outer joint of df1 and df2 can be created using:
A right joint of df1 and df2 can be done using:
You can find other methods too but in my approach this is the best one.