Equi-join

Tables are joined using the primary key of one table and the foreign key of the other table.

Generic

SELECT *
    FROM table1, table2
    WHERE table1.primaryKey = table2.foreignKey;

Example

Note: In this example both tables have a field with the same name. So that the database can distinguish between the fields they must be qualified with the table name. Just using the field name would be ambiguous.

SELECT *
    FROM Pet, Vaccination
    WHERE pet.petID = vaccination.petID;