TOPIC:COLLECT  ONE  ER  DIAGRAM  EXAMPLE  WITH  EXTENDED  ER  FEATURES  &  EXPLANATION.

 

QUESTION

 

ER  diagram  of  a  CARGO  MANAGEMENT  SYSTEM  is given below:

A crew of people will be controlled by a captain.A vessel can have crew of people but that crew of people can be present only in one vessel.In a vessel,the captain have the right to command.Ship are of two types-Vessel and SOTL.Many regions are patrolled by vessels and many vessels patrols many regions to make sure that  there is no trouble there.

  • Crew is uniquely identified by name.It also consist of age,rank.
  • Captain is uniquely identified by name.
  • Ship is uniquely identified by ship name.It also consist of flank speed, displacement.
  • Region is uniquely identified by region name.
  • SOTL consist of  class name,size primary,num_primary.

 

 

 

ANSWER

 

1.IDENTIFY THE ENTITY

  •  CREW
  •  CAPTAIN
  •  SOTL
  •  VESSEL
  •  REGION
  • SHIP

2.IDENTIFY THE RELATION

-A CREW OF PEOPLE IS CONTOLLED BY A CAPTAIN.

Cardinality-1:1

 

-MANY CREWS ARE ASSIGNED TO ONE VESSEL.

Cardinality-n:1

 

-CAPTAIN COMMANDS IN A VESSEL.

Cardinality-1:1

 

-SHIP IS DIVIDED INTO TWO ie VESSEL AND SOTL.

 

-MANY REGIONS ARE PATROLLED BY MANY VESSELS.

Cardinality-n:n

 

3.IDENTIFY THE KEY ATTRIBUTES.

CREW-CREW_NAME

CAPTAIN-CPTN_NAME

REGION-REGION_NAME

SHIP-SHIP_NAME

 

4.OTHER RELEVANT ATTRIBUTES.

  • CREW

CREW_NAME

AGE

RANK

  • CAPTAIN

CPTN_NAME

  • SHIP

SHIP_NAME

FLANK_SPEED

DISPLACEMENT

  • REGION

REGION_NAME

  • SOTL

CLASS_NAME

SIZE_PRIMARY

NUM_PRIMARY

 

5.COMPLETE ER DIAGRAM.

 

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