Mode disclosure
All modes use one coherent workspace; only disclosure and guidance change. Practice mode uses a concise prompt, normal schema, optional hints, and the same local Run and Check pipeline.
HAVING, Conditional Aggregation, and Safe Ratios / compare queries
M15-A01 - Classification - place six conditions in WHERE or HAVING
M15-A01 - Classification - place six conditions in WHERE or HAVING. Filter groups, compute conditional metrics, and calculate safe rates.
- Result grain
- one clause-placement decision per condition
- Exact columns
- condition_no; condition_text; clause_choice
SQL editor shortcuts: Ctrl or Command Enter runs the query, Ctrl or Command Shift Enter checks it, Alt H opens the next hint, Ctrl or Command slash toggles a line comment, Ctrl or Command Shift F formats the SQL, and Escape closes transient UI.
Cursor at line 1, column 1.
Scenario
Filter grouped reports and calculate conditional metrics deliberately: separate WHERE from HAVING, make conditional populations explicit, and protect ratios with numeric division and NULLIF.
HAVING, Conditional Aggregation, and Safe Ratios / compare queries
One-sentence task
M15-A01 - Classification - place six conditions in WHERE or HAVING. Filter groups, compute conditional metrics, and calculate safe rates.
Practice mode disclosure
Concise prompt, normal schema help, optional hints, and the same checker workspace are available.
Structured output contract
- Result grain
- one clause-placement decision per condition
- Exact columns
- condition_no; condition_text; clause_choice
- Source population
- Use the prompt setup plus FROM, JOIN, WHERE, and subquery predicates as the source population. Visible rows are only examples.
- Grouping
- Do not collapse rows unless the contract explicitly asks for aggregation, distinct tuples, or set semantics.
- Ordering
- order by condition_no
- Validation
- select-only; hidden deterministic variants.
Relevant tables
Time and difficulty
- Estimated time
- 5 minutes
- Difficulty
- 3/5
Objective and concepts
Practice mode keeps the prompt concise; open hints only if you choose guided help.
Assumptions, dialect notes, and common traps
- Duplicate policy
- Preserve duplicate facts unless the prompt explicitly asks for distinct tuples or set semantics.
- Null policy
- Preserve NULL, empty string, zero, and false as distinct values unless the contract says to display a fallback.
- Tie-breakers
- Use every ordering rule in the contract and end tied business metrics with deterministic secondary keys when needed.
- Zero-related entities
- Do not invent zero rows unless the contract asks for preserved parents, missing entities, or complete periods.
- Numeric tolerance
- Use exact semantic comparison unless the activity explicitly declares a numeric tolerance.
Opened hints
No hints opened yet.