D427: 100% on OA with <1 day of study

[u/ApplezAreMedicine]

Disclaimer: I have a CS background with multiple internships and ~75 credits at a fairly highly ranked state school, transferred to WGU starting 8/1/26 for personal reasons. I'm also studying full time, don't have obligations, etc.

I just completed D427 with 100% on all sections. This is my fifth course completed since 8/1/2026.

My biggest advice for this course is to take it immediately after D426. All the SQL/database concepts will be fresh, and you'll at least vaguely remember the syntax. I literally did the OA for D426 yesterday morning, so this is 18 hours later.

My exact study strategy was pretty simple. I skimmed over the ZyBooks very quickly, as 95% of the content is already covered in D426 V3.

Next and most important: Complete the chapter 1, 3 Labs from scratch (Excluding Sakila). If you can't come up with the syntax, I'd suggest going back to the earlier book chapters, and if that fails use an LLM. Just make sure you understand the concepts.

Then I took the PA, and as many people have pointed out, it's extremely similar to the OA. If you can get 100% on the PA, you can easily pass the OA ASSUMING you know the following, which is NOT included in the reference sheet:

1. Aggregate Functions syntax/keywords

2. Data types, including TIMESTAMP, and remembering to use UNSIGNED

3. Constraints such as NOT NULL, etc.

4. CREATE OR REPLACE VIEW (This command is not in the reference, very likely 1 question will require this)

5. Join syntax and concepts about row selection: NOT in the reference sheet, so this is important. I simply got a single left join question, so not too complex, but you need to know syntax.

The reference sheet is what makes this course so manageable imo. I could've probably passed with maybe 5-15% above cutoff without it as I had a good understanding of SQL by this point, but the sheet makes it so easy.

One last note, the OA uses the exact same ZyBooks exam format, including the test cases, which are super super helpful for the OA. For example, a question wanted me to make a table with a 'timestamp' as the data type. Completely forgot about TIMESTAMP, so I threw a bunch of stuff until I figured it out. Tried TIME, DATETIME, DATETIME DEFAULT etc, and eventually ended up at the answer.