## Materials

material_id | name | cost
--- | --- | ---
1 | Concrete | 30.0
2 | Steel Rebar | 60.0
3 | Lumber | 20.0
4 | Bricks | 15.0
5 | Cement | 45.0

## Projects

project_id | name | start_date | end_date | infrastructure_id
--- | --- | --- | --- | ---
|  |  |  | (→ Infrastructure.infrastructure_id)
1 | Highway Bridge Repair | 2023-01-01 | 2023-07-31 | 1
2 | Road Paving | 2023-05-01 | 2023-10-31 | 2
3 | Building Foundation | 2023-03-01 | 2023-09-30 | 3
4 | Stadium Construction | 2023-08-01 | 2024-02-28 | 4
5 | Park Improvement | 2023-06-01 | 2023-12-31 | 5

## Infrastructure

infrastructure_id | description | service_life_expectancy_id | renewal_schedule_id
--- | --- | --- | ---
|  | (→ Service_Life_Expectancy.service_life_expectancy_id) | (→ Renewal_Schedule.renewal_schedule_id)
1 | Bridge Abutment | 1 | 1
2 | Retaining Wall | 2 | 2
3 | Foundation Slab | 3 | 3
4 | Earthwork Embankment | 4 | 4
5 | Drainage System | 5 | 5

## Workers

worker_id | first_name | last_name | skill_level
--- | --- | --- | ---
1 | John | Smith | 8
2 | Jane | Doe | 9
3 | Mike | Johnson | 7
4 | Emily | Williams | 9
5 | David | Brown | 8

## Tasks

task_id | description | assigned_to_worker_id | due_date | completed
--- | --- | --- | --- | ---
|  | (→ Workers.worker_id) |  |
1 | Repair concrete cracks | 1 | 2023-07-15 | 0
2 | Install new drainage system | 2 | 2023-10-01 | 0
3 | Replace steel rebar | 3 | 2023-09-15 | 0
4 | Paint bridge abutments | 4 | 2023-11-15 | 0
5 | Level retaining wall | 5 | 2023-12-15 | 0

## Service_Life_Expectancy

service_life_expectancy_id | min_years | max_years
--- | --- | ---
1 | 20 | 40
2 | 15 | 30
3 | 30 | 60
4 | 10 | 20
5 | 5 | 15

## Renewal_Schedule

renewal_schedule_id | frequency
--- | ---
1 | Yearly
2 | Quarterly
3 | Semiannually
4 | Monthly
5 | Annually