Query Writing Skill
Workflow for Simple Queries
For straightforward questions about a single table:
- Identify the table - Which table has the data?
- Get the schema - Use
sql_db_schemato see columns - Write the query - SELECT relevant columns with WHERE/LIMIT/ORDER BY
- Execute - Run with
sql_db_query - Format answer - Present results clearly
Workflow for Complex Queries
For questions requiring multiple tables:
1. Plan Your Approach
Use write_todos to break down the task:
- Identify all tables needed
- Map relationships (foreign keys)
- Plan JOIN structure
- Determine aggregations
2. Examine Schemas
Use sql_db_schema for EACH table to find join columns and needed fields.
3. Construct Query
- SELECT - Columns and aggregates
- FROM/JOIN - Connect tables on FK = PK
- WHERE - Filters before aggregation
- GROUP BY - All non-aggregate columns
- ORDER BY - Sort meaningfully
- LIMIT - Default 5 rows
4. Validate and Execute
Check all JOINs have conditions, GROUP BY is correct, then run query.
Example: Revenue by Country
sqlSELECT c.Country, ROUND(SUM(i.Total), 2) as TotalRevenue FROM Invoice i INNER JOIN Customer c ON i.CustomerId = c.CustomerId GROUP BY c.Country ORDER BY TotalRevenue DESC LIMIT 5;
Error Recovery
If a query fails or returns unexpected results:
- Empty results — Verify column names and WHERE conditions against the schema; check for case sensitivity or NULL values
- Syntax error — Re-examine JOINs, GROUP BY completeness, and alias references
- Timeout — Add stricter WHERE filters or LIMIT to reduce result set, then refine
Quality Guidelines
- Query only relevant columns (not SELECT *)
- Always apply LIMIT (5 default)
- Use table aliases for clarity
- For complex queries: use write_todos to plan
- Never use DML statements (INSERT, UPDATE, DELETE, DROP)
