This professor definitely has changed from the previous quarters, I'm not feeling anything negative mentioned in the previous reviews in his class.

Took this class Spring2020 and it seemed like Rosario took a lot of feedback based on the previous negative reviews.

His tests were very fair and honestly on the easier side if you attended lecture and did the hw. He's very clear and has a good understanding of all the material so I made sure to attend all lectures.

He previously had large coding projects as a part of the class but this quarter instead chose to do smaller psets, which made the courseload very manageable.

He has good insights on the applications of databases due to his industry experience. Highly recommend you take this class with him

His pace is fast, and it's hard to stay engaged. Miss a lecture or two, and you have to play catchup immediately. I think the curriculum is almost too packed with a huge breadth and a lot of depth within the breadth, so our attention is spread thin. However, Rosario is a really helpful guy who genuinely cares about teaching and helps his students. The projects have kinks that need to be ironed out (project 2B at one point blocked my teammate and I for 12 hours), but I feel like I learned the most practical knowledge taking this class out of any of my upper division CS courses. He's an industry guy (works/worked at Facebook, Amazon, Google) and I think we need more of that here at UCLA. He's polarizing among my classmates but I really gained a lot from taking the course with him.

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edit: heavy emphasis on polarizing.... some of the reviews on here act like he’s the worst, a 0/10. Simply not true. If you only focus on the bad and the BS about assignments/tests (which is semi-abundant), then I understand really disliking his teaching. But if you genuinely want to learn databases, you’re gonna learn very relevant stuff w Rosario. You’ll learn some not so relevant stuff too (what’s new in cs upper divs), but this class is a nice departure from the theory-only classes that are frequent here at UCLA. Though I will say that the lack of clarity and communication on projects was frustrating, and people are justifiably mad about it. If that can get fixed for the future, then this professor is the one to take.

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TL;DR: if you’re here to absorb as much practical knowledge as you can, and can stomach some BS and perhaps a B or lower for that, then Rosario is tailored for you. But if you aren’t and/or you want a relatively easy and simple upper-div (which is totally cool, I feel ya), you shouldn’t take him. Don’t believe the hype about how bad he is. He’s been one my favorite professors so far here at UCLA, but evidently not for a lot of other people lol.

This is one of the most useful classes at UCLA. I've interned at a few well-known tech companies, and having a strong understanding of databases, SQL, and transactions is super important. Professor Rosario centers this class around preparing you for industry, because he's worked at Facebook, Google, and Amazon and he knows what we need to succeed.

There's a highly vocal group of anonymous students here who are downvoting any sort of positive feedback because they are upset about the difficulty of the final and/or their grade in the course. Notice that most of the negative reviews were written June 20-23ish, 2019, which is around the time that final exam grades and letter grades for the class were released. Don't always trust the upvotes/downvotes on each review. I'll offer a change by focusing on positive aspects, which is something I believe everyone should do rather than unleashing their hate just because they have a platform that makes them anonymous.
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First, our Piazza forum had almost 900 posts, but the professor basically answered all of them. Yup, some students received unenlightening replies or were instructed to go to office hours when they asked about things that were discussed repeatedly in lecture, but most students who politely asked reasonable questions got helpful answers -- within MINUTES -- from the professor himself. If a professor did not care about his students, would he answer practically all of the students' concerns within 1-10 minutes when he could just assign the task to the TAs like other "oh so caring" or in other words "gives lots of A's" professors do? Do other professors stay up until midnight the day before the 8am final exam to answer all last-minute questions from students, like this professor does?
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Second, the professor is actually really nice and friendly in person. During the break and after class, I've seen students approach him and ask a few questions, and the professor would typically respond with a friendly smile and often laugh lightheartedly. If good questions came up during the break, he would announce them and clarify things to the entire class as soon as the class resumed. He also held extra office hours during Weeks 2-10 upon requests from students, and he held extra office hours during Finals Week that spanned several hours as well.
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Third, his projects were pretty interesting and sometimes fun although they were difficult. They were much more practical than other professors' projects, some of which were last updated a decade ago. He also gave extra credit on the projects, and they weren't too difficult as long as you planned ahead.
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Fourth, the professor is truly loyal to UCLA and gave several inspirational pep talks throughout the quarter. He mentioned how he did horribly in some classes here at UCLA but that it did not affect his professional career. He name-dropped several prestigious jobs he held and companies he worked for in the past to illustrate that grades don't dictate our future.
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All of my friends like this professor, and so does a good chunk of the class, which is evident because a lot of students continued to go to lecture even though it was at 8am. Students often laughed at the professor's memes and jokes, and generally had feel-good vibes as the class came to a close. We applauded the professor not once but twice at the end of the last lecture to express our appreciation. The emotional, vocal minority here on Bruinwalk does not reflect all 200+ students in the class. However, I do understand these students' struggles because this class definitely pushed us hard in terms of assignment workload, exam difficulty, and denseness of class material. Let's just remember to be nice to others even when we're anonymous so that we can collectively strengthen our community, do good things out there, and be regarded with greater respect from those outside the Bruin family.

He is a genuinely helpful professor, who is always trying his best to help us learn and improve.

There are some harsh reviews for Professor Rosario here on Bruinwalk. This is more than a little bit surprising to me, as I had an excellent experience taking 143 with him over the summer. Professor Rosario was an engaging lecturer, answered questions well, and was very helpful during office hours. There are several mentions of bullying/micro-aggressions among the other reviews, and given that they are from the same quarter during which I took the class, I must have missed them. All I can testify is that he was friendly and helpful during lectures and office hours and never gave any indications of being rude or dismissive with me that I could pick up on. I felt that the workload was on the easier end for the computer science department, although Eggert has skewed my perspective on normality, and the final was based off of the class (not an accomplishment, but then again we deal with some silly stuff here) and didn't jump out as being particularly unreasonable. It wasn't necessarily the best class I've ever taken but it didn't stand out as a negative experience. I'm only adding my review so that people know that the narrative that Rosario is an asshole is not a universal experience and perhaps should be taken with a grain of salt.

The professor was really nice and helpful. He answered Piazza posts extremely quickly and thoughtfully.

We had a mini-project for extra credit. This probably bumped my grade up from B+ territory up to an A.

I'm not sure how good his lectures are, since I just looked over the slides, but from the brief snippets of the recording I saw, they seemed okay. His slides, however, are very good, IMO.

There were only 5 homework assignments, and the workload for each of these was not too bad. I think each of these assignments could be done in an afternoon.

The midterm was okay, but the final was a bit harder. I just reviewed the lecture slides, homework assignments, and discussion slides. I received a 88% for the midterm and 80% for the final.

The recent reviews don't lie; the class, and professor rosario, have improved since a majority of the reviews were left. I took it online and we had 5 homeworks, 1 extra credit project with spark, a midterm, and a final. All of which were pretty straightforward, and the curve prof rosario gives is pretty generous. Additionally, I never felt like prof rosario was belittling students like some previous reviewers mentioned; I asked some pretty dumb questions in office hours and class, and never once did prof rosario make me feel like an idiot (even though I probably am at times). I'm not too interested in databases, but I'd recommend most CS majors to take some offering of this course to get a fundamental understanding of databases.

I remember seeing Rosario get a lot of from prior Bruinwalk reviews and actively tried avoiding him - then I took his class and realized how WRONG those reviews were. He's completely revamped the curriculum post 2019 and it's solid.

Rosario is awesome. His lectures are clear + engaging and follow the slides in lock step (he posts slides prior to lecture, annotates during class, and re-posts after).

Best thing about him is he works in industry as a Data Scientist / SWE, so every topic is covered with practical, real-world examples that we can actually use.

And he's a nice guy who truly enjoys teaching, and he handled COVID better than any other professor I've seen so props!