Explode a Bill of Materials

SQL practice question · Hard · Recursive & Hierarchy · Oracle

bom says how many units of child_part go into ONE unit of parent_part. A top-level product is a part that appears as a parent but never as a child; a base part never appears as a parent. Sub-assemblies can be shared and nested to any depth. For every top-level product return product, base_part and total_qty (units of that base part needed to build one product, summed over all paths). Order by product, base_part.

Table: bom

Schema of bom
ColumnType
parent_partTEXT
child_partTEXT
qty_perREAL
Sample rows of bom
parent_partchild_partqty_per
BIKEFRAME1
BIKEWHEEL2
WHEELSPOKE32
WHEELRIM1
WHEELTUBE1
FRAMESTEEL_TUBE4
FRAMEBOLT6
WHEELBOLT2
Expected output on the sample data
productbase_parttotal_qty
BIKEBOLT10
BIKERIM2
BIKESPOKE64
BIKESTEEL_TUBE4
BIKETUBE2

Solve it in the live editor on this page — run on sample data, then submit against hidden tests.

‹ Consecutive Failed Job Runs · Average Time Spent In Progress ›

T
Tech Town
Log InSign Up Free
Home SQL Python DSA Power BI Snowflake Databricks Spark Gen AI Practice Problems Contest Question Asked in Interview Blog
SQL Interview Practice

Company-wise SQL questions

{{ totalCount }} questions in the style asked at Amazon, Microsoft, Google, Meta, Flipkart and more — {{ hardPct }}% Hard. Write SQL in a real database engine in your browser, run it on sample data, then evaluate against hidden tests.

🏆 Weekly SQL Contest
{{ totalCount }}
Questions
{{ companyCount }}
Companies
{{ prog.total.solved }}
Solved
Bookmark Question Companies Difficulty Category Status
{{ r.n }} - {{ r.title }} {{ c }} {{ r.difficulty }} {{ r.category }} {{ r.statusIcon }}
No questions match these filters.
Showing {{ rangeLabel }} of {{ filteredCount }}

Company tags show where this type of question is commonly reported in interviews. Questions, data and solutions are written by TechTown.
← All questions

{{ cur.n }} - {{ cur.title }}

🏆 Contest {{ contestWeek }}
{{ cur.catLabel }} {{ cur.diffLabel }} {{ c }}
Embed this questionPaste on a blog, course page or LMS. Free to use — educator guide 
{{ embedCode }}

{{ cur.statement }}

Table: {{ tb.name }}
ColumnType {{ c.name }}{{ c.type }}
{{ h }} {{ v.text }}
Expected output on the sample data:
{{ h }} {{ v.text }}
  • {{ h }}

No submissions yet. Press Evaluate to submit your query.
{{ s.verdict }} {{ s.meta }}
The solution unlocks after you solve this question or after 3 evaluations that didn't pass ({{ failCount }}/3 so far). Trying first is the fastest way to learn. 
{{ solutionSql }}
  1. {{ e }}
⏱ {{ timerLabel }}
{{ fnHelpTitle }}
{{ fnHelpText }}
Writing {{ dialectName }} · Ctrl/Cmd + Enter runs the query · Tab indents · your code is saved automatically
Output {{ out.status }}
  • {{ w }}
    •
{{ out.verdict }}
{{ out.detail }}
 
{{ out.error }}
Expected (sample data)
{{ h }}{{ v.text }}
Your output (sample data)
{{ h }}{{ v.text }}
{{ h }} {{ v.text }}
Run your query to see the result here.
🔒

To Track Your Progress, Log In / Sign Up

You have solved your 3 free questions — nice work! Log in (free) to unlock all 150 questions, keep your streak and appear on the leaderboard.

Sign Up Free Log In