Caused by: org.hibernate.MappingException: Repeated column in mapping for entity

You have two column mapped with the same name

 @JoinColumn(name = "fid_module", referencedColumnName = "id_activity")
 @JoinColumn(name = "fid_module", referencedColumnName = "id_event")

Change one of the name attribute!

Looking in your exception, you can read:

Repeated column in mapping for entity

As noted in another answer, your Java code specifies the same join-column name for two fields, which can't work.

If this Java code is generated by a netbeans mapping tool, as it seems from your note

Now the mapping I did with the help of Netbenas and gave me the following code ...

the bad Java mapping is probably caused by a bad combination of constraints in your SQL.

You have in your definition of the photo table:

  CONSTRAINT fk_photo_activity FOREIGN KEY (fid_module)
      REFERENCE activity (id_activity) MATCH SIMPLE
      ON UPDATE NO ACTION ON DELETE NO ACTION,
  CONSTRAINT fk_photo_event FOREIGN KEY (fid_module)
      REFERENCE event (id_event) MATCH SIMPLE
      ON UPDATE NO ACTION ON DELETE NO ACTION

which attempts to make the column fid_module a foreign key referencing activity and also a foreign key referencing event, which can't work.

If you need foreign keys from photo to both of those tables, you'll need to use two different columns.