MySQL query to select from different tables and group data [duplicate] - mysql

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How do I generate nested json objects using mysql native json functions?
(4 answers)
Closed 6 years ago.
I have some tables about tv shows. Also I have one of the pages where I show where user can see some seasons and episodes.
CREATE TABLE `tv` (
`tv_id` int(11) UNSIGNED NOT NULL PRIMARY KEY AUTO_INCREMENT,
`title` VARCHAR(30),
`rating` float(2,1) DEFAULT NULL,
`total_seasons` tinyint UNSIGNED,
)
CREATE TABLE `tv_player_episode_mapping` (
`tv_id` int(11) UNSIGNED,
`season` tinyint(11) UNSIGNED,
`episode` tinyint(11) UNSIGNED,
`player_id` tinyint(11) UNSIGNED,
`file_name` TEXT
);
CREATE TABLE `player` (
`player_id` int(11) UNSIGNED NOT NULL PRIMARY KEY AUTO_INCREMENT,
`hostname` VARCHAR(30),
UNIQUE KEY `name` (`hostname`)
);
To select a data from a table I use this query:
SELECT tpe.season, tpe.episode, p.hostname, tpe.file_name, t.rating, t.total_seasons
FROM tv_player_episode_mapping tpe
INNER JOIN player p ON p.player_id = tpe.player_id
INNER JOIN tv t ON t.tv_id = tpe.tv_id
WHERE tpe.tv_id = 1;
Below is the result of query and here the problem - some data like total_seasons and ratins repeated:
[
{
file_name:"19891-molodoy-papa.html",
hostname:"kinoclub.cc",
season: 1,
episode: 1,
total_seasons: 1,
rating: 8.5,
},
{
file_name:"19891-molodoy-papa.html",
hostname:"kinoclub.cc",
season: 1,
episode: 2,
total_seasons: 1,
rating: 8.5,
}
]
I try to change my query to get somethink like this (I am novice in databases and I think this is good structure for response from the server):
{
total_seasons: 1,
rating: 8.5,
players: [
[ // Here first element of array `playes` is array for season 1
[ // Episode 1
{
file_name:"1-1-the-young-pope.html",
hostname:"my-player.io",
},
{
file_name:"1-1-the-young-pope.html",
hostname:"another-one-player.io",
}
],
[ // Episode 2
{
file_name:"1-2-the-young-pope.html",
hostname:"my-player.io",
},
{
file_name:"1-2-the-young-pope.html",
hostname:"another-one-player.io",
}
],
],
[] // Season 2
]
};
But because I am little experienced in databases I stop trying with this query and can't find the way:
SELECT tpe.season, tpe.episode,
JSON_OBJECT(
'total_seasons', t.total_seasons,
'players', JSON_OBJECT('hostname', p.name, 'file_name', tpe.file_name))
FROM tv_player_episode_mapping tpe
INNER JOIN player p ON p.player_id = tpe.player_id
INNER JOIN tv t ON t.tv_id = tpe.tv_id
WHERE tpe.tv_id = 1;
How can I change this query to solve my problem?
UPD:
I wrote some query using example and I am good with it, but now result of my query looks strange.
New query:
select json_object(
'rating', t.rating,
'total_seasons', t.total_seasons,
'players', json_array(
(select GROUP_CONCAT(
json_object(
'hostname', p.hostname,
'file_name', tpe.file_name,
'season', tpe.season,
'episode', tpe.episode
)
)
FROM tv_player_episode_mapping tpe
INNER JOIN player p ON p.player_id = tpe.player_id
INNER JOIN tv t ON t.tv_id = tpe.tv_id
where tpe.tv_id = 52)
)
)
from tv t WHERE tv_id=52;
Result of query:
{
"json_object( 'rating', t.rating, 'total_seasons', t.total_seasons, 'players', json_array( (select GROUP_CONCAT( json_object( 'hostname', p.hostname, 'file_name', tpe.file_name, 'season', tpe.season, 'episod":
"{\"players\": [\"{\\\"season\\\": 1, \\\"episode\\\": 1, \\\"hostname\\\": \\\"kinoclub.cc\\\", \\\"file_name\\\": \\\"19891-molodoy-papa.html\\\"},{\\\"season\\\": 1, \\\"episode\\\": 2, \\\"hostname\\\": \\\"kinoclub.cc\\\", \\\"file_name\\\": \\\"19891-molodoy-papa.html\\\"},{\\\"season\\\": 1, \\\"episode\\\": 1, \\\"hostname\\\": \\\"kinoclub.cc\\\", \\\"file_name\\\": \\\"123.html\\\"}\"], \"rating\": 8.5, \"total_seasons\": 1, \"rating\": 8.300000190734863}"
}
What can I do to format result like this?
{
total_seasons: 1,
rating: 8.5,
players: []
};

Answer 1

The short answer is no, but you still can partially implement JSON like structure by using group_concat function.
Example:
SELECT x, y, concat('[', group_concat(z), ']') as z FROM tbl group by x, y;
Will give you answer like:
x y z
1 2 [3,4,5]
6 7 [8,9,10]