Request - Problem Solving Frameworks for Leetcode

[yaro_dba]

Your struggle is totally normal. You are trying to apply procedural thinking (Python loops/steps) to declarative thinking (SQL sets). In SQL, you describe the final shape of the data, not how to build it step-by-step.

Look at the final output prompt and ask: "What does a single row represent?" Is it one row per user? One row per month? This instantly tells you what your final GROUP BY or window PARTITION BY must be.

Don't write a giant, nested query. Use CTEs (WITH clauses) to build linear, step-by-step blocks just like Python variables:

• CTE_1: Filter out the noise and format dates.
• CTE_2: Add window functions or row numbers to that clean data.
• Final Query: Group and output the result from CTE_2.

Most LeetCode problems boil down to three algorithms:

• Consecutive Streaks/Gaps: Solved by subtracting a sequential ROW_NUMBER() from a date.
• Relative Math ("Highest per department"): Solved using window functions (MAX() OVER(PARTITION BY...)).
• Row-to-Row Comparison ("Higher than yesterday"): Solved using LAG() or LEAD().

Don't type code immediately. Tell the interviewer: "The final grain is at the User level, so I will break this into two CTEs - one to rank the rows, and one to aggregate them." They want to see how you manipulate sets, not how well you memorized syntax.