MY-ASSIGNMENTEXPERT™可以为您提供units ST207 Database数据库课程的代写代考和辅导服务！
这是维多利亚大学 数据库课程的代写成功案例。
NIT1201课程简介
This unit introduces fundamental concepts and principles of database and explains its role and purpose in information system design and analysis. Students gain mastery of standard techniques to identify system requirements and design a simple database system. Content includes: systems concepts; role of the analyst; Systems Development Life Cycle (SDLC), process modelling, Entity-Relationship (ER) modelling; relational database design using ER and Extended ER modelling, SQL (Structured Query Language), normalisation; and database management systems (DBMS).
Prerequisites
On successful completion of this unit, students will be able to:
- Describe the benefits and functions of databases and their applications;
- Design a database using key relational database model concepts;
- Develop and apply entity relationships (ER) and extended entity relationships (EER) diagrams;
- Implement a relational database with multiple tables using a relational DBMS;
- Apply query languages and manage a database using SQL; and
- Normalise relations in a relational database system.
NIT1201 Database HELP（EXAM HELP， ONLINE TUTOR）
What are all of the candidate keys for this table?
The candidate keys are State, Abbrev, and Title. Each of these by itself guarantees uniqueness so it is a superkey. Each contains only one column so it is a minimal superkey, and therefore a candidate key.
All of the other fields contain duplicates and any combination that doesn’t have duplicates in the data shown (such as Engraver/Year) is just a coincidence (someone could engrave two coins in the same year). That means any superkey must include at least one of State, Abbrev, or Title to guarantee uniqueness, so there can be no other candidate keys.
If you don’t allow two people with the same name to share a room (due to administrative whimsy), what are all of the possible candidate keys for this table?
Room/FirstName/LastName and FirstName/LastName/Phone/CellPhone are the possible candidate keys.
CellPhone can uniquely identify a row if it is not null. If CellPhone is null, then we know that Phone is not null because all students must have either a room phone or a cell phone. But roommates share the same Phone value, so we need FirstName and LastName to decide which is which. (Basically Phone/CellPhone gets you to the Room.)
If you do allow two people with the same name to share a room, what are all of the possible candidate keys for this table?
In this case, FirstName/LastName is not enough to distinguish between roommates. If their room has a phone, they might not have cell phones so there’s no way to tell them apart in this table. In this case, the table has no candidate keys. That might be a good reason to add a unique column such as StudentId. (Or if the administration assigns rooms, just don’t put two John Smiths in the same room. You don’t have to tell them it’s because of your poorly designed database!)
What field-level check constraints could you put on this table’s fields? Don’t worry about the syntax for performing the checks, just define them.
The room numbers are even so you could use Room Is Even. (Don’t worry about the syntax for checking that a value is even.) You could also use some simple range checks, such as (Room $>=100$ ) AND (Room $<300$ ), depending on what room numbers are actually allowed. You might also notice that every Phone value has the same area code and exchange 202-237, so you could check for that.
MY-ASSIGNMENTEXPERT™可以为您提供units ST207 Database数据库课程的代写代考和辅导服务！
