Selecting a Primary Key - Essay Example

EmailThen you would create a third entity “Nametel” that will have a telephone number and Record number as both the primary key and foreign key5. Provide an example of when you would use a “recursive” relationship.If for instance, we have a table where a company has branches it will be the parent company. Therefore:Company idParent idCompany nameA1NullEquity headquartersA2A1Equity Kerugoya branchA3A1Equity Miiria branchA4A2Equity Kerugoya mtaani shopA5A3Equity Miiria main shopGiven that the headquarters has branches and those branches are parent companies for the main shop6.

A database table contains the field “QatarID” as a primary key. Should the data type of this field be text or number? Explain.It should be number because texts make bad primary keys as for texts there is a chance it might repeat itself.7. What is the purpose of a “use case” diagram in UML modeling?In order to define interactions between a role which is refered to as an actor and a system in order to achieve a specified goal8. Identify one (1) cost-saving and one (1) cost increase that might be incurred if CNAQ were to introduce an online student registration system.

If CNAQ were to introduce an online student registration system the cost-saving reported would be a reduced amount of cash used to buy printing papers and the cost increase incurred would be for creating the system and for maintaining it9. A systems analyst would like to estimate the cost of installing wireless access points in a college building. In a similar installation last year, the cost was 200,000 QAR. It is estimated that in this installation, the cost will be 15% higher. If a contingency reserve of 10% is to be included in the calculation, determine the estimated cost.

Show all working.Installation cost excess: 200000*0.15=30000Total installation cost: 200000+30000=230000Total installation cost + contingency reserve: 1.1*230000=253000Total estimated cost: 25300010. A project manager has been asked to estimate the cost of upgrading a company’s network servers. She comes up with three scenarios for the cost:Most likely: 250 000 QARPessimistic: 400 000 QAROptimistic: 200 000 QARDetermine a three-point estimate for the upgrade. Show all working.Take; E as the Estimate, and as the best-case estimate, b as the most likely estimate and c as the worst-case estimate Therefore;a = 200000 , b = 250000 and c = 400000we find,E=(a +b +c)/3 E=(200000+250000+400000)/3E=(850000)/3E=283333.

33Therefore E = 283333.33 QARDue date: Thursday 29 November before 5:00 pmSUBMISSION INSTRUCTIONS1 ALL assignments to be submitted electronically in MS Word format through the college e-mail system. 2 Put your name and student number in the HEADER of the word document3 The file name must include your student number, last name, initial, the course number, and assignment number. E.g., if your name is Ali Al Kaabi, student number 600444905 then the file name would be: 600444905, Al Kaabi, A, CR2350 Assignment 54 The subject of your e-mail must be “CR2350 assignment 5” 5 I will deduct 10% from your assignment mark if you do not follow these conventions.