# Computer science assignment | Computer Science homework help

Please see the attached file for the actual assignment. It has the images.

The following ER Diagram represents the data model for a maritime system that will track the movements of ships visiting ports and their home ports

(1) Create a relational schema .  (listing of table structure with attributes that includes specification of keys and lines+arrows addressing foreign keys) for this data model

(2) Write the create table statements in SQL with propto1 er syntax 5 points] (make assumptions about data types, make sure to include keys/foreign keys, think carefully about how to handle the weak entity and the many many relationship)

(3) Provide a definition or answer:

(A) From a database perspective, data can be classified into two types: atomic and compound. a. Define atomic  b. Define compound

(B) If a relation A has 4 attributes (hence degree 4) and 7 tuples, and relation B has 3 attributes and 5 tuples what is the degree and size of A X B?

(C) Define Primary Key:

(D) Define Foreign Key:

(4)   (10 points) For the relation:

What is a valid (composite, candidate) key?

Explain in writing why it is a valid key and why other choices are not:

(5)   (10 pts) Describe at least 3 different type of JOINs and how they differ.

(6)  (15 pts)  Given relation Table1(A,B,C):      And relation Table2(A,B,C):             4 (A) Provide the relation for Table1  ∩ Table2:       4 (B) Provide the relation for Table1  – Table2:       4 (C) Compute (Table1  – Table2)     (Table2  – Table1), often called the “symmetric difference” of Table1 and Table2.      A B C 1 2 3 4 2 3 4 5 6 2 5 3 1 2 6 A B C 2 5 3 2 5 4 4 5 6 1 2 3 5)  (8 pts) Based on the tables below, provide the relation for TableB  ÷ TableA: TableA PNO Desc 8 Rachet & Socket 10 Hammer 14 Screwdriver  TableB Emp PNO Desc John 8 Rachet & Socket John 10 Hammer Bill 14 Screwdriver Mary 10 Hammer Mary 14 Screwdriver Bill 8 Rachet & Socket John 14 Screwdriver Mary 12 Saw 6) (1 pts ) Write a series of relational algebra statements 2 pizza SQL database we looked at that that based on the relations in will implement: “Find the names of all people who eat at least one pizza served by the Little Caesars not frequent Little Caesar s . ” but who do not frequent Little Caesar s . ”

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