Reference no: EM13509145
1Explain why the addition of NOT NULL constraints to the SQL de?-nition of the Manages relation (in Section 3.5.3) does not enforce the constraint that each department must have a manager. What, if anything, is achieved by requiring that the ssn ?eld of Manages be non-null?
2.Consider the scenario from Exercise 2.2, where you designed an ER diagram for a university database. Write SQL statements to create the corresponding relations and capture as many of the constraints as possible. If you cannot capture some constraints, explain why.
3.Consider the scenario from Exercise 2.4, where you designed an ER diagram for a company database. Write SQL statements to create the corresponding relations and capture as many of the constraints as possible. If you cannot capture some constraints, explain why.
4.Translate your ER diagram from Exercise 2.6 into a relational schema, and show the SQL statements needed to create the relations, using only key and null constraints. If your translation cannot capture any constraints in the ER diagram, explain why.
In Exercise 2.6, you also modi?ed the ER diagram to include the constraint that tests on a plane must be conducted by a technician who is an expert on that model. Can you modify the SQL statements de?ning the relations obtained by mapping the ER diagram to check this constraint?
|
Compute the simple rate of return for 2009
: The Marcus Corporation purchased a piece of new equipment in January 2009 for $120,000. The equipment was depreciated using the straight line method over an 8 year life without a salvage value.
|
|
What are the dimensions of viscosity
: The drag force acting on a sphere moving through a liquid like water is given by F=6?vr? where F is the drag force, v is velocity of the sphere, r is radius of the sphere, What are the dimensions of viscosity
|
|
Determine the payback period of the investment
: Would the payback period be affected if the cash inflow in year 8 was $18,000?
|
|
Define net present value of the investment
: The management of Ocala Company is considering the purchase of a $25,000 machine that would reduce operating costs by $4,000 per year. At the end of the machine's 10 year useful life, it will have a zero salvage value. The company requires a 14% o..
|
|
Consider the scenario from exercise 2.4 where you designed
: Consider the scenario from Exercise 2.4, where you designed an ER diagram for a company database. Write SQL statements to create the corresponding relations and capture as many of the constraints as possible. If you cannot capture some constraints, e..
|
|
Calculate the marginal product of each worker
: Calculate the marginal product of each worker. What principle explains why the marginal product per worker declines as the number of workers employed increases?
|
|
What is the total work done on the box
: A 5kg box is pushed across a level floor with a net force of 50 N in the direction of the displacement of 10m. What is the total work done on the box
|
|
Fastenals cost from lost sales of current customers
: What is Fastenals cost from lost sales of current customers - using a relevant cost analysis should Fastenalt accept Hank's special order?
|
|
Find the normal force exerted by the pivot
: A woman of massm=50.1kg sits on the left end of a seesaw-a plank of lengthL=3.99m-pivoted in the middle, Find the normal force exerted by the pivot if the plank has a mass ofmpl=10.2kg
|