Level 1 · Day 1
Start with SQL
Learn what a table is and write your first SELECT. Pick the rows you need and sort them.
UnlocksYou can pick rows and columns and sort them the way the question asks.
OA Helper
14 levels, one a day. 11 topics and 110 real OA questions, from your first SELECT to window functions.
Level 1
First levelStart with SQL
Play level 1Every placement season, we watch the same thing happen.
You prepare DSA for months. Then the OA opens, and there are two SQL questions you did not see coming. You studied SQL once, in a college subject, two years ago. You know what a JOIN is. But you have never written one with a timer running and hidden test cases checking every row. Ten minutes go. Then twenty. The marks go with them, and sometimes the shortlist does too.
That is not because you are not good enough. Nobody showed you how these questions are actually asked.
So we built this for that one gap. Fourteen days, one topic a day, and every practice question here was asked in a real company OA. It is short on purpose, because you have a lot else to prepare.
Start with Day 1, even if it looks easy. That is where you learn how the judge reads your output, and it is where most people lose their first marks.
When that SQL question shows up in your OA, we want you to smile at it.
The OA Helper team
Level 1 · Day 1
Learn what a table is and write your first SELECT. Pick the rows you need and sort them.
UnlocksYou can pick rows and columns and sort them the way the question asks.
Level 2 · Day 2
Find totals, averages and counts. Group rows by city or department with GROUP BY.
UnlocksYou can answer "how many per city" and "average per department".
Level 3 · Day 3
Count only the rows that match a rule using CASE WHEN. Turn rows into columns.
UnlocksYou can make a small report with one column per status.
Level 4 · Day 4
Combine two or three tables with JOIN. Keep the rows that have no match too.
UnlocksYou can join students, offers and companies without losing rows.
Level 5 · Day 5
Compare a table with itself. Find customers who never ordered, or staff who earn more than their manager.
UnlocksYou can answer "who earns more than their manager" and "who never ordered".
Level 6 · Day 6
Break one big question into small steps with WITH. Combine the results with UNION.
UnlocksYou can write a two step answer without getting confused.
Boss level · Day 7
12 mixed questions from Week 1 in 90 minutes. No notes, like a real OA.
UnlocksYou know which topics of the week need one more look.
Level 8 · Day 8
Second highest salary. Top 3 in every department. The most asked SQL interview question.
UnlocksYou can solve the most asked SQL interview question in three ways.
Level 9 · Day 9
Compare a row with the one before it. Running totals and streaks of consecutive days.
UnlocksYou can find day on day growth and three days in a row attendance.
Level 10 · Day 10
Group by month, count the days between two dates, and cut text like an email into parts.
UnlocksYou can group by month and cut a name or email into parts.
Level 11 · Day 11
Long questions with three or four tables. Read them fast and solve them step by step.
UnlocksYou can read a long question in two minutes and plan the answer.
Theory level · Day 12
Keys, normal forms, indexes, ACID. 40 quick answers for the interview round after the OA.
UnlocksYou can answer the theory round the day after the OA.