You should fully discuss and/or respond to each of the following items. Include

Question

You should fully discuss and/or respond to each of the following items. Include the item number and related text at the beginning of your discussion for each item. Prepare your discussion for all six items in one Word document and then upload the file to your eLearn dropbox for this course In priority order, list the three most important points made by your instructor in each of the presentation videos for this chapter. Do not simply put down key words or bullets but use a paragraph with 2-3 sentences for each important point. (4pts) Describe referential integrity and explain importance of foreign keys in mainitaing referential integrity in database design. Include a specific implementation example in your description and explanation. (6pts) Define and give an example for each of the following database terms as each one relates to discussion in the video presentations for this chapter: restrict, cascade, and set-to-null. 9pts) 1. 2. 4. Review Exercise 2 on Page 154 in your textbook. Construct a relational database, including tables, to handle the enitics, attibutes, and relationships included in the exercise. For each relation (table) in your relational database, cleatly specify, primary key, alternate key(s), and foreign keys. (9pts) Review Exercise 3 on Page 154-155 in your textbook. Construct a relational database including tables, to handle the entities, attributes, and relationships included in the exercise. For each relation (table) in your relational database, cleatly specify, primary key, alternate key(s), and foreign keys. (12pts) 40 points allowed for this assignment.

Explanation / Answer

2.Referential integrity is a relational database concept, which specifies that table relationships must always be consistent. Any foreign key field must match with the primary key that is referenced by the foreign key.

e.g

In a student table class teacher ID is a foreign key but for a teacher relational database ,teacher ID is a primary key.

It is important to maintain a consistency in it because any change in foreign key can produce irregularities or mismatch in content.

3.

restrict-It restrict the deletion or updation in parent table if it is used in any child table.

cascade-It specifies if there is any change in foreign key then all the relations that are using it as a fkey they must be updated automatically.

set to null- It specifies null value for any attribute which is not availble yet.

4.

fire department relation

Id name year ph_no

234 NewYork 1981 4568901

278 sanfransisco 1945 4092874

Primary key- Id

alternate key -Id name

firefighter relation

firefight_no name Id_dept year_cert tel rank superv

q237 max 234 2003 892222 junir millen

i982 ary 236 2009 346777 asst liport

primary key -firefight_no

foreign key- Id_dept

supervisor relation

firefight_id name Id_dept

q234 millen 234

i987 liport 237

foreign key-firefight_id,Id_dept

primary key-name,firefight_id

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