Mapping Exercise Exercise 7.4. Date FIGURE 7.7 Timestamp An ER schema for a SHIP_TRACKING Time SHIP_MOVEMENT Longitude database. Latitude HISTORY Туре Tonnage Hull SName N 1 SHIP TYPE SHIP_TYPE Owner (0,") StartDate EndDate HOME_PORT (1,1) Name VISITS VISITS Continent (0,") N IN STATE/COUNTRY PName PORT Name ON SEAVOCEANLAKE

Implement a new independent entity phone in the Sakila database. Attributes and relationships are shown in the following diagram: The diagram uses Sakila naming conventions. Follow the Sakila conventions for your table and column names: All lower case Underscore separator between root and suffix Foreign keys have the same name as referenced primary key Write CREATE TABLE and ALTER TABLE statements that: Implement the entity as a new phone table. Implement the has relationships as foreign keys in the Sakila customer, staff, and store tables. Remove the existing phone column from the Sakila address table. Step 2 requires adding a foreign key constraint to an existing table. Ex: ALTER TABLE customer ADD FOREIGN KEY (phone_id) REFERENCES phone(phone_id) ON DELETE SET NULL ON UPDATE CASCADE; Specify data types as follows: phone_id, phone_number, and country_code have data type INT. phone_type has date type VARCHAR(12) and contains strings like 'Home', 'Mobile', and 'Other'. Apply…

(Choose all of the correct superkeys.) Find all superkeys of the DEPARTMENT relation. Its primary key (PK) is underlined.                DEPARTMENT (number, dname, mgrssn, location)                PK = {dname, location} {number} {number, dname} {number, dname, mgrssn} {number, dname, mgrssn, location} {dname} {dname, mgrssn} {dname, mgrssn, location} {mgrssn} {mgrssn, location} {location} {number, dname, mgrssn} {number, dname, location} {number, mgrssn} {number, mgrssn, location} {number, location} {dname, location}

What three situations make it necessary to make a substitute key instead of the main key of a relation?

Here are three examples of when it makes sense to create a surrogate key in place of the primary key in a relation.

For merging two relations that are not physically sorted but share an index on the characteristics in question, it is necessary to develop a hybrid merge-join method.

Primary key identifies a unique tuple of a relation, true or false?

Apply the normalization process to the Das Auto relation shown below to develop a set of normalized relations. Show the results of each of the steps in the normalization process.   CarMake CarModel Year CarType LicensePlate State OwnerLastName OwnerFirstName OwnerPhone OwnerEmail Service Date Charge BMW 330i 2020 Sedan 20487963 MA Yee Lucy 205-304-6598 lucy.yee@gmail.com Oil Change 8/9/2020 $     80.00 Mercedes-Benz C280 2006 Sedan 31598769 NH Koka Bardhyl 301-987-9354 bardhyl.koka@yahoo.com Brake Hose Replacement 5/9/2020 $  550.00 Audi S5 2018 Convertible CH 06874 MA Jones Andy 547-963-5478 andy.jones@gmail.com Fuel Pump Replacement 5/9/2020 $  423.00 Porsche Cayenne 2014 SUV LH 05879 NH Papa Katie 512-568-7849 katie.papa@aol.com Brake Pads 6/3/2020 $  232.00

explanation of three circumstances where a substitute key for a relation's primary key should be created?