If you fail the SQLD even after learning SELECT and JOIN in your major courses, it is natural to be confused about whether you are incapable of SQL or if your study method was wrong. The failure review of a major who took the 62nd SQLD illustrates precisely this point.
To start with the conclusion, the SQLD is less of a test of recalling learned material and more of a test of accurately distinguishing between similar concepts and SQL execution results. In this post, I will summarize why the study period for a major did not guarantee a pass, the reasons for failure, and the study sequence for retaking the exam, along with actual reviews.
The reason even majors failed the SQLD
The SQLD consists of two subjects: Understanding Data Modeling and SQL Basics and Application, with a total of 50 questions. Since Subject 1 has 10 questions and Subject 2 has 40, those who have only mastered SQL syntax are likely to lose points in the Data Modeling section.
The majors who took the 62nd exam had already learned databases and SQL at school. Although SELECT, WHERE, GROUP BY, HAVING, JOIN, and ORDER BY were not unfamiliar, it was analyzed that the reason for failure was that they glossed over the detailed concepts simply because they were familiar.
What you learn once in class is different from the ability to pick out the correct answer on a test. In particular, if the wording of the options changes even slightly, you may get concepts you thought you knew wrong, and even if you get a question right, if you cannot explain the reason for the answer, it will remain a weak area in the actual exam.
Major-specific knowledge gives you an early start, but it does not replace the practice of choosing the correct answers from past exam questions.
Exam structure and perceived difficulty
The passing criterion is a total score of 60 points or higher without failing any subject. Since receiving a score of 40% or lower in any subject results in a failing grade regardless of the total score, a strategy of focusing on only two subjects and postponing one is risky.
The exam is not a practical test where you write queries yourself, but rather a multiple-choice format where you read SQL statements and concepts. However, you cannot prepare solely by rote memorization. If problems arise that require calculating SQL execution results or determining the order of multiple conditions, your time to solve them will decrease rapidly.
The perceived difficulty varied in the reviews. Some found the confusing terminology in data modeling the most difficult, while another candidate stated that they missed more questions in Subject 2 than in Subject 1. Ultimately, which subject is difficult depends on prior experience and the volume of practice problems solved.
How to interpret a one-month study period
The major in question began studying with a focus on concepts one month before the exam. However, since daily study hours and total study volume were not disclosed, rather than accepting the standard that "one month is sufficient," you should examine what was repeated during that period.
In the beginning, I learned the concepts using books and study materials, and grasped the overall structure by watching the Adapter SQLD lectures on YouTube once. Afterwards, I transcribed the content myself while referring to the concept summaries on the website, and solved past and reconstructed questions from SQLD Yangpa.
The problem is The fact that the exam is approaching before you have sufficiently reviewed past questions and incorrect answersAt the last minute, I added the yellow book known as 'SQL Certification Practice Problems,' but as I hurriedly encountered new problems, the time to solidify existing concepts decreased.
Conversely, other success stories show a wide range of intensive study periods, from instances where the study duration was limited to just a few days to cases where students started a month before the exam and immersed themselves for over a week. Since major experience, adaptability to the questions, and daily study volume vary, it is difficult to judge the likelihood of passing based solely on the duration.
Problem-solving methods to prevent failure
| division | Main range | Points that are easy to miss when studying |
|---|---|---|
| 1 subject | Understanding Data Modeling | You must distinguish between similar terms and sentence expressions. |
| 2 subjects | SQL Basics and Applications | Execution results and conditional flow are more important than memorizing grammar. |
| entire | Total of 50 questions | You must secure a total score of 60 or higher while avoiding failing grades. |
A method was proposed to allocate the weight to concepts and problems as approximately 30–401 TP3T for concepts and 60–701 TP3T for problem-solving and incorrect answers. In the retake plan, this was organized more specifically by dividing it into 301 TP3T for concepts, 501 TP3T for past exams and problem-solving, and 201 TP3T for incorrect answers.
In the first step, quickly read through the entire scope once to create a big picture. At this stage, rather than trying to perfectly memorize everything, it is more efficient to mark the areas you are likely to get confused about, such as data modeling, NULL, subqueries, aggregation, and WHERE clauses.
From the second step onwards, focus on past exam questions and reconstructed problems. You must include not only the questions you got wrong but also those you answered correctly by guessing or for which you could not explain the reasoning in the incorrect answer list to avoid falling into the same trap in the next session.
When the results of an SQL execution feel complex, try drawing a small table instead of processing them in your head. If you write down the changes in rows, the timing of the application of WHERE and HAVING, and the results generated by JOIN step-by-step, the differences between the options will become visible.
Studying by explaining why each option is right or wrong is remembered longer than studying by memorizing the correct answer numbers.
Change the order like this for a retry
If you are preparing for a retake, it is more appropriate to quickly skim the scope of the exam by reading through the concepts once, rather than listening to the lectures multiple times from the beginning. Majors should not spend excessive time on SELECT or JOIN operations they are already familiar with, but instead focus on checking data modeling and theories they find confusing through practice problems.
Non-majors should first learn the basic flow of SELECT, WHERE, GROUP BY, HAVING, and ORDER BY rather than immediately repeating past exam questions. Then, if you expand the scope to JOIN and subqueries, it becomes easier to identify where conditions are applied when reading long SQL statements.
You should not simply review incorrect answers once and be done with them; you must solve them again at regular intervals. If you briefly review only the concepts related to the incorrect problems and then re-solve them a few days later with the answers hidden, you can distinguish between simple rote memorization and actual understanding.
Right before the exam, rather than adding new study materials, it is better to review key expressions in data modeling and common SQL topics such as NULL, subqueries, and regular expressions. Since time may feel tighter in the actual exam than in mock tests, you should practice including the time for marking rather than dwelling on long questions.
The key to retaking the SQLD lies not in extending the study period, but in the process of transforming concepts into problems and re-solving incorrect answers. Majors should guard against the sense of knowing, while non-majors will find their learning direction much clearer if they establish the flow of basic grammar first before moving on to past exam questions.