Instructor: Jing Gong

Weekly Question #4 (Due Friday, September 25)

Leave your response as a comment on this post by the beginning of class on September 25, 2015. Remember, it only needs to be three or four sentences. If you sign in using your AccessNet ID and password you won’t have to fill in the name, email and captcha fields when you leave your comment. Answer one of the two questions below:

(1) Do you encounter any trouble setting up MySQL Workbench or running simple SQL statements? If so, please describe your problem as a comment on this blog post. That way you can get help from fellow students or me, and share your experience with everyone else.

(2) Our review for the first exam is during class on October 2. What question about the material we’ve covered so far would you like to discuss during the review?
(NOTE: Focus on your understanding of the material, not “will x be on the exam?”!)

41 Responses to Weekly Question #4 (Due Friday, September 25)

  • 1. Personally, I did not experience any difficulties setting up MySQL Workbench or running simple queries. I have some minor prior experience with SQL and love running statements.

    2. I would like to get a quick refresher on the ER Diagrams. From the first assignment, it was difficult for me to pick out from the paragraph which should be entities and which should be attributes. As well as how to connect (relationship) the various entities.

  • From everything that we have learned so far, I would like to review more about the ERD diagrams. Sometimes it gets a little bit confusing of which ones connect to which ones. Moreover it is confusing sometimes to differentiate which cardinality to use.

  • 1. With the use of the guide, in class examples, class capture and PPT’s I did not have much trouble installing MySQL Workbench. The only problem I ran into was knowing whether to download the 32 bit version or the 64 bit version. After a bit of trial and error, I realized my computer was compatible with the 32 bit version.

    2. I feel as though I lack confidence in the accuracy of my ERD diagrams. I personally did not feel 100% comfortable doing the homework ERD diagram assignment and felt as though it was more advanced than the examples we covered in class. I would like to review this more. I was also wondering if we will be using ERDPlus on the exam for the ERD diagrams or if we are going to draw them by hand.

    • Hi Jason, The exam will be paper-based. Therefore you will have to draw ERDs by hand. Make sure that you bring pencils and erasers.


  • My first question about the key material for the exam is the use of the key demands in MySQL. I am really confused as to which ones to use at which times (other than SELECT and FROM) and the meaning of these demands. I was hoping during our review session. We can go over these again. Also during the review, I was hoping we could go over helpful ways to understanding cardinalities. I feel like I am over thinking them and there is probably an easier way to understand them.

  • I believe the hardest thing to understand from MySQL is when we have to pull from multiple tables in order to try and select one option, because the written line of code is often 6 or more lines which can result in some confusion. I also believe that the ERD diagrams and cardinalities are somewhat confusing, and I often over thing the relationship and cardinalities between two entities.

  • Personally, I have not fully grasped the concept of how to construct schemas and then draw the ERD diagrams. I am not confident reading a scenario and then having to make schemas and draw the ERD diagrams. In relation to the diagrams, I also would like to further review how to choose the proper cardinality. Being that we will have to draw the ERD diagrams on the exam, I would like to review this further.

  • I still have problems when combining multiple tables for one problem in MySQL. However, it helps to be able to test to the queries on the MySQL program. Doing them by hand on the exam will be much more difficult because you won’t be able to test them. Additionally, I think that it would be helpful to go over ERD cardinality again before the exam.

  • Pertaining to the upcoming exam; I would like to go over the ERD model and identify the relationships between the entities, more clarity in this area can help much. Maybe we can do a comparison of an ERD relationship with an identical schema relationship. Taking the table primary keys and matching them to the foreign keys. The confusion is coming more from the many to many relationships and the one to many relationship, I am not sure what side to put the relationships on(meaning outside or the inside for each)
    Another example of the join table could be helpful also.

  • 2) I would like more examples of ERD diagrams. The homework assignment was way more complicated than any ERD diagram we did in class, so I felt under prepared. I dont think I am ready to constrict an ERD diagram on an exam yet, and it is difficult to practice this outside of the classroom.

  • 2) I believe that I have grasped the concept of ERD diagram since we have done some examples as well as an assignment on it. However, I still feel uncomfortable with creating a schema since we have not done any example questions on it. I am not sure how the question for schema will be like. Will it be the same as an ERD diagram where the question will be in paragraphs and we have to construct an ERD diagram then convert it into a schema or will we be given an ERD diagram and be asked to convert it into a Schema?

  • I made small errors such as misspelling words, and not including quotes where they are needed. After the SQL statement did not run, I was able to figure out the issues pretty quickly.

    I would like to discuss creating SQL statements from a question, and go over examples that we try on own own. Also, I would like to go over ERD and schema examples.

  • I do not have much trouble running simple SQL statements. However, I sometimes have trouble determining exactly what to type when the instructions are not given. It is important to understand the SQL statements.

  • I personally think SQL is easier than ERD, because all we need to do in SQL is just memorizing the statement and how they work. I have more troubles in doing ERD especially in Assignment 1 which is so much harder than what we have done before. I would like to go over how to use ERD to reflect entities, attributes and most importantly relationships in paragraphs. As for SQL, also going over the statements are also important.

  • I wish to go over more about ERD diagrams because it’s easy to get lost in the problem statement on which is considered entities, attributes, and the relationships between them like from assignment one. Cardinality can get confusing as well, especially when you have to make assumptions. The conversion between ERD diagrams and schema tables is another thing I would like more review. For MySQL, combining multiple SQL statements to one SQL statement to solve some questions could get difficult

    • Totally agreed. Speaking of assumptions, sometimes it’s hard to make sure whether or not your assumptions are right .

  • 1) My issue trying to set up MySQL was during the download process, the directions were good. However, I just thought I had to download two Microsoft versions of MySQL and then go back onto the page and download the 64 bit and or 32 bit. Once I realized what I was doing wrong I haven’t had a problem since (I just have to make sure that I am typing everything in correctly).

  • My main difficulty with running SQL statements was when it came to using the “MAX” function. Attempting to figure out how to build this function into a sub select took a long period of time for me to grasp.

  • 2. The biggest concern that I had was over the results of assignment 1. I did not do as well as I thought I did and it looks like I was having trouble identifying entities and whether or not it was a one to one, one to many, or many to many relationship. Prior to the exam, it would be beneficial for me to discuss the difference in whether or not something is simply a noun or whether it is an entity and how the relationships are determined between entities. Overall, my question would be what is a proper method that we should use in order to ensure we are determining these relationships accurately?

  • Of all the things we’ve cover I would like to talk more about ERD diagrams. Out of all the material this is what I’m having the hardest time understanding. Also, I don’t fully understand schemas, that whole process is confusing to me and I think going over that and knowing exactly what is expected of us on the test would be beneficial.

  • (1) On the initial day in class when we first started SQL I wasn’t able to attend the entire class, as my train arrived late so I missed the first half of class. However, after a few times trying to sign in it finally worked. The issue for me was remembering which statements go to each column. Then once I was signed in and was doing the in-class practice simulations some of them would not register. I believe it was because of a small typo in my SQL code. For example, reading the SQL statement correctly and knowing where to put spacing and the exact statement needed to pull up the information requested.

  • I did not not experience much difficulty setting up the My SQL workbench. However, the statements are challenging at points because there is not much instruction given sometimes. Therefore, it is challenging to come up with the right sequence. In terms of the exam, I would like to go more over the ERD modeling. I will use the 20 minute video to study however, I would like to see more examples of different situations.

  • During our exam review I wish to review ERD diagrams and schemas again. I feel uncomfortable going into the exam without further reviewing this topic. The in class diagrams were less complicated then the homework assignment and I want to be prepared to construct a diagram on the exam.

  • For exam 1, I would like to discuss more of constructing an ERD model and how exactly to identify the relationships between entities. I feel like I am good enough to gather the correct attributes with their entities, however going over the relationships and the overall process of creating an ERD would be beneficial. Also, I am not confident in converting it to a schema model and having the exact relationships in place.

  • 1. I haven’t experienced any problems.

    2. I think more review on ERDs would be helpful as they are complicated and challenging. For me personally the hardest part of making an ERD diagram is knowing which entities relate to each other.

  • I am basically fine with all the material we went over in class. I would definitely want to go over and review the cardinalities, sometimes they can get confusing on which side they go on and how to figure how which ones to use. Other than that I have been reviewing the material for this exam.

  • I would like more review on the ER diagrams. Specifically, it would be helpful to review when there are very many relationships between entities. Also, I was not entirely certain how to include unique key identifiers. Lastly, I would benefit from a review on making schemas from ER diagrams.

  • 2). I would like to go over ER modeling, specifically go over all the various relationships.

  • 1) I had absolutely no issues setting up MySQL on my personal laptop or any issues utilizing it in class on the class computer terminals. The instructions were more than adequate. As far as I can tell, the only thing that will pose a challenge will be syntax and memorization of the fundamental – and more vital – commands. Nothing to do there but practice and see real-life examples of the queries in use.

    2) I feel relatively comfortable with ERD’s; however, I wouldn’t mind going through cardinality rules once more with a few challenging examples (similar to what we will be exposed to on the exam) to work out and get immediate feedback to clarify ambiguity. The video concerning the ERD assignment was helpful, but now that we are all much more familiar, a run-through with some examples during the review session would probably be the best option for the class. I understand joins will not be covered on Exam I, but I would like more exposure to when relationship tables are specifically necessary (I am under the impression that they’re only needed between M:M relationships, and none other).

  • So I far, the most tricky part was analysing the cardinality between entitiy to entitiy. This is because I have to figure out by self.
    With MYSQL Workbench, I had no problem so far. But I wanna know localhost to practice(manipulating tables) by my self.

  • Hi Ms Gong,

    I’m confused of the relationships of Ride,Operator and Incident about the Assignment 1, so in the solution that you showed us, Ride and Operator is a m:m relationship which is a ride is related to many operators and it’s the same the other way around. A Ride can involve many incidents, and incident is only related to one ride, so here’s the question: If a ride can have many operators, and an incident can be related at most one ride, why is an incident can only relate to at most one operator?

    • Hi Weiming, this is because the problem statement explicitly mentioned that “An incident involves both a ride and an operator.” Each time a ride runs, it is operated by one operator. The many-to-many relationship reflects the fact that over time, there can by many operators running the same ride. But each time, there is only one operator running the ride. -Jing

  • My biggest question about the upcoming exam right now is probably the format. I may have missed you going over it in class, but I was wondering whether it was online and maybe involves screen shots or saved files. I’ll be sure to think of more questions before the day of the exam!

  • 1. I would love to discuss cardinality during the review as it created several complications for me when completing the first assignment. My inability to understand how to properly indicate and evaluate the cardinality in the relationship between two entities lost me significant credit and creates distress for my academic experiences in this course. Also, since class never technically started Friday, then my submission cannot technically be considered late as it was due at the beginning of a class that was cancelled.

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