Create a logical ERD for each of the problems on the following pages using the crowsfoot notation discussed in class. Be sure that each entity has the entity name at the top of the box, the primary key attribute or attributes in the middle of the box, and the non-key attributes in the bottom of the box. Lines should separate each part of the entity box. Follow these instructions about each ERD:

• The ERD should not have any many-to-many (M:N) relationships.
• All attributes should be placed within an entity.
• Each entity must have a primary key defined. A primary key may consist of one or more attributes.
• Each relationship must have a foreign key. Denote the foreign key(s) with the notation (FK) on the ERD. It is not necessary to number the foreign keys, but if you do that would be nice.
• Each relationship must include both a maximum and minimum cardinality for both sides of the relationship.
• Each relationship must have a relationship verb.
• Remember that 1:1 relationships are rare. Make sure that you carefully scrutinize any 1:1 relationships to ensure that they are actually 1:1.

Question #1. Design a database to help a chemical engineering organization keep track of the assignment of equipment and employees to projects. The organization has several employees who work on one or more projects. Employees also may use certain kinds of equipment on each project. Attributes of EMPLOYEE include EmployeeID (identifier), EmployeeName, and PhoneNumber. Attributes of PROJECT include projectID (identifier), ProjectName and StartDate. Attributes of EQUIPMENT include SerialNumber (identifier) EquipmentType, and cost.

The organization wishes to record the AssignDate that is the date when a given equipment item was assigned to a particular employee working on a specified project. The organization also wants to keep track of the ReleaseDate the date when a given equipment item was released from an employee working on a specified project.

An employee must be assigned to at least one project. An employee may be assigned to multiple projects. An employee may or may not be assigned to an item of equipment. A given equipment item need not be assigned to a project or to an employee. A given project need not be assigned either an employee or an equipment item. A given equipment item can only be assigned to one project at a time. A given equipment item can only be assigned to one employee at a time. The organization wants to be able to assign an employee to a project, even if there is no item of equipment to assign. The organization also wants to be able to assign an item of equipment to a project, even if there is no employee to assign.

Here is a heads-up: No part of a primary key can be null for any row in an entity. We use the word null in database lingo to indicate data that is non-existent. We frequently create attributes in a database design that may have a null value at one time or another. In the scenario above, it is likely that the attribute ReleaseDate will be null when an employee is originally assigned to a project or to an item of equipment. That is perfectly OK. It is OK to design data attributes that may have non-existent data at some time during the processing of an application that uses the database. It is NOT OK to use that data attribute for all or part of a primary key.