Uhusiano Maradufu na Jedwali Moja katika PHP

Wacha tuwe na miji:

cities
id	name
1	city1
2	city2
3	city3

Wacha tuwe na njia kati ya miji, wakati kila njia ina mwanzo wa mji na mwisho wa mji:

routes
id	name	from_city_id	to_city_id
1	route1	1	2
2	route2	2	3

Wacha tuseme tunataka kupata njia pamoja na miji. Ugumu hapa unawakilishwa na ukweli kwamba kila njia ina miji miwili: mwanzo na mwisho.

Inabadilika kuwa jedwali la miji linahitaji kujiunga mara mbili. Kwa kila muunganisho jedwali italazimika kubadilisha jina:

sqlSELECT
  from_cities.name as from_city_name,
  to_cities.name as to_city_name
FROM
  routes
LEFT JOIN cities as from_cities
  ON from_cities.id=routes.from_city_id
LEFT JOIN cities as to_cities
  ON to_cities.id=routes.to_city_id

Задание 1

Wacha tuwe na watumiaji. Kwa kila mtumiaji ana baba na mama. Andika muundo wa uhifadhi.