sql/event_data_objects.cc:
  Add module comments.
sql/event_data_objects.h:
  Add module comments.
sql/event_db_repository.cc:
  Add module comments.
sql/event_db_repository.h:
  Add module comments.
sql/event_queue.cc:
  Add module comments.
sql/event_queue.h:
  Add module comments.
sql/event_scheduler.cc:
  Add module comments.
sql/event_scheduler.h:
  Add module comments.
sql/events.cc:
  Add module comments.
sql/events.h:
  Add module comments.
sql/lock.cc:
  Add module comments.
sql/sp_head.h:
  Add module comments.
sql/sql_base.cc:
  Add module comments.
sql/sql_lex.h:
  Add module comments.
sql/sql_parse.cc:
  Add module comments.
sql/sql_select.cc:
  Add module comments.
sql/sql_yacc.yy:
  Add module comments.