Table inside of another - php

Question

I want to plan my trips publicly so other people can join me. So, I have set-up an PHP site.
I have this tables:
trips:
+----+---------+------------+------------+-------------------------+
| id | title | date_start | date_end | marker_adress |
+----+---------+------------+------------+-------------------------+
| 1 | Berlin | 2015-07-10 | 2015-07-11 | Potsdamer Platz, Berlin |
| 2 | Hamburg | 2015-07-16 | 2015-07-18 | Jungfernstieg, Hamburg |
+----+---------+------------+------------+-------------------------+
fellows:
+----+---------+---------------+
| id | trip_id | twittername |
+----+---------+---------------+
| 1 | 1 | prtyengopls |
| 2 | 1 | itobi_yt |
| 3 | 1 | jessisadancer |
| 4 | 2 | jessisadancer |
| 5 | 2 | woelfch3n |
+----+---------+---------------+
For displaying sake, I want to query them in one query. How can I query the database so I have something like this? (I know, it's JSON but it shows the structure very well.)
{
"id": 1,
"date_start": "2015-07-10",
"date_end": "2015-07-11",
"marker_adress": "Potsdamer Platz, Berlin",
"fellows": [
{
"id": 1,
"twittername": "prtyengopls"
},
{
"id": 2,
"twittername": "itobi_yt"
},
{
"id": 3,
"twittername": "jessisadancer"
}
]
}

Answer 1

First you have to use a LEFT JOIN like this:
SELECT
t.id AS tripID,
t.title AS title,
t.date_start AS dateStart,
t.date_end AS dateEnd,
t.marker_address AS markerAddress,
GROUP_CONCAT(DISTINCT CAST(f.id AS CHAR)) AS fellowID,
GROUP_CONCAT(DISTINCT CAST(f.twittername AS CHAR)) AS twitterName
FROM trips t LEFT JOIN fellows f ON t.id = f.trip_id
GROUP BY t.id
By using this you will get a single row for each trip and you can loop over fellowID and twitterName for each row, as it will be comma delimited list like this:
fellowID: 1,2,3
twitterName: prtyengopls,itobi_yt,jessisadancer
Edit 1: I got a new column to trips called checked which is a boolean.
Could you update your query, so only trips that have this boolean
toggled on are displayed?
SELECT
t.id AS tripID,
t.title AS title,
t.date_start AS dateStart,
t.date_end AS dateEnd,
t.marker_address AS markerAddress,
GROUP_CONCAT(DISTINCT CAST(f.id AS CHAR)) AS fellowID,
GROUP_CONCAT(DISTINCT CAST(f.twittername AS CHAR)) AS twitterName
FROM trips t INNER JOIN fellows f
ON t.id = f.trip_id AND t.checked = 1
GROUP BY t.id

Answer 2

I don't think it's possible like you expected in SQL. Just to answer your question and show you the problem: you have to use a join (left, inner or something ... depends of your database structure; I always prefer left joins if possible) to get all information in just one query:
SELECT * FROM trips t LEFT JOIN fellows f on t.id = f.trip_id WHERE t.id = 1;
But you always will get the trip information with every row, and for that you have to process it afterwards. You will never able to select such a nested structure, you will always get a flat one.
So I would recommend to split it into two queries like this:
SELECT * FROM trips WHERE id = 1;
SELECT * FROM fellows WHERE trip_id = 1;
You will have to process the information afterwards too, but you just select the wanted information from your database.
Hope that helps.