SQL practices
===

### ToC

- [Practice 1](#practice-1)
- [Practice 2](#practice-2)
- [Practice 3](#practice-3)

# Practice 1

- Count the number of subordinate 'ENTERPRISE\_CUSTOMER' organizations for each organization.

```sql
SELECT
    COUNT(customers.*) AS "subordinates_count",
    organizations.id AS "id"
FROM organizations
LEFT OUTER JOIN enterprise_sales_enterprise_customers customers ON customers.sales_organization_id = organizations.id
GROUP BY organizations.id
ORDER BY organizations.id ASC
;
```

# Practice 2

- Calculate the center of each `japan_segment`.

```sql
SELECT
    id,
    ST_X(ST_Centroid(bounds)) AS "longitude",
    ST_Y(ST_Centroid(bounds)) AS "latitude"
FROM japan_segments
;
```

# Practice 3

- Select `japan_segments` within the bounds represented as the following GeoJSON.

```json
{
  "type": "FeatureCollection",
  "features": [
    {
      "type": "Feature",
      "properties": {},
      "geometry": {
        "type": "Polygon",
        "coordinates": [
          [
            [
              130.27313232421875,
              30.519681272749402
            ],
            [
              131.02020263671875,
              30.519681272749402
            ],
            [
              131.02020263671875,
              30.80909017893796
            ],
            [
              130.27313232421875,
              30.80909017893796
            ],
            [
              130.27313232421875,
              30.519681272749402
            ]
          ]
        ]
      }
    }
  ]
}
```

![Kagoshima segments](./img/kagoshima_segments.png)