Window Functions Query Builder

Build a query using window functions for this requirement:

**Tables:**
```sql
{{TABLE_SCHEMA}}
```

**Requirement:** {{REQUIREMENT}}

Examples:
- Running totals
- Rankings
- Moving averages
- Lead/lag comparisons
- Percentile calculations
- Row numbering with partitions

**Database System:** {{DATABASE_SYSTEM}}

Please provide:
1. The complete query with window functions
2. Explanation of each window function used
3. PARTITION BY and ORDER BY rationale
4. Frame specification explanation (ROWS/RANGE)
5. Alternative approaches without window functions
6. Performance comparison
7. Sample output with explanation