Implement SQL challenge: 6 queries + pytest suite (11 tests)

[shobitgupta-ui]

Summary

Implemented weasb_sql_test technical challenge: 6 SQL queries + pytest suite.

Queries

• create_employees.sql: Employee roster with manager relationships
• create_expenses.sql: Itemized expense receipts
• create_invoices.sql: Supplier & invoice tables (alphabetical IDs, EOM normalization)
• find_manager_cycles.sql: Circular approval chain detection (recursive CTE)
• calculate_largest_expensors.sql: Expense accountability report (KEY QUERY)
• generate_supplier_payment_plans.sql: Monthly payment schedule

Testing

• pytest suite: 11 test cases (all passing)
• Validates: schema, threshold enforcement (>1000), sorting, null handling

Implementation

• Recursive CTE for cycle detection
• Window functions for deterministic ID assignment
• Type-safe DECIMAL for currency
• Comprehensive edge case handling
• 90+ lines of comments per query