SELECT FLD1, FLD2 FROM TABLE1 INNER JOIN TABLE2
ON TABLE1.PRIMARY_KEY=TABLE2.FOREIGN_KEY
OR
SELECT FLD1, FLD2 FROM TABLE1 , TABLE2
WHERE TABLE1.PRIMARY_KEY=TABLE2.FOREIGN_KEY
Above we are matching the fields of both the tables and extract the record only when the record exists in both the tables.
In case of Inner join above both are same and you can use as you like.