如何对数组中的特定字段进行分组？

编程问答 2021-09-15

问题描述

由一个名叫Ghost的大师提供，这是一个将一维数组转换为多维数组的简单示例…

<?PHP

$my_array = array();
$my_array =
array
(
    0 => array
        (
            id => '4',
            project_id => '2289',
            task => 'Drawing'
        ),

    1 => array
        (
            id => '5',
            project_id => '2289',
            task => 'Surveying'
        ),

    2 => array
        (
            id => '6',
            project_id => '2289',
            task => 'Meeting'
        ),

    3 => array
        (
            id => '1',
            project_id => '2282',
            task => 'Folding'
        ),

    4 => array
        (
            id => '2',
            project_id => '2282',
            task => 'Printing'
        ),

    5 => array
        (
            id => '3',
            project_id => '2282',
            task => 'Cutting'
        )

);

$new_array = array();
foreach ($my_array as $row) {
   $new_array[$row['project_id']]['project_id'] = $row['project_id'];
   $new_array[$row['project_id']]['task'][] = $row['task'];
}

$new_array = array_values($new_array); // reindex
// removes `$row['project_id']` on each group

print_r($new_array);

?>

输出：

Array
(
    [0] => Array
        (
            [project_id] => 2289
            [task] => Array
                (
                    [0] => Drawing
                    [1] => Surveying
                    [2] => Meeting
                )

        )

    [1] => Array
        (
            [project_id] => 2282
            [task] => Array
                (
                    [0] => Folding
                    [1] => Printing
                    [2] => Cutting
                )

        )

)

解决方法

我需要trophies获得一支球队的胜利，每个奖杯都是在特定赛季的比赛中获得的，但是一支球队可以在每个不同季节的同一场比赛中赢得奖杯。

我写了一个查询，从数据库中提取奖杯：

$sql = $this->db->prepare("SELECT t.*,s.*,c.*,t.team_id as team_id,s.id as season_id,s.name as season_name,c.id as competition_id,c.name as competition_name
    FROM team_trophies t
    INNER JOIN competition_seasons s ON s.id = t.season_id
    INNER JOIN competition c ON c.id = s.competition_id
    WHERE team_id = :team_id
  ");

从本质上讲，我trophies从表中选择了特定团队的所有球员，team_trophies并加入了competition_seasons以获取奖杯的赛季细节，与competition表中相同。

这有效，我得到：

[
    {
        "team_id": "23291","season_id": "2","position": "Winner","wins": "4","id": "1093","competition_id": "1093","name": "Premier League","update_at": "2018-06-04 12:12:30","country_id": "1","category": "1","season_name": "2017","competition_name": "Premier League"
    },{
        "team_id": "23291","season_id": "3","position": "Runner-up","wins": "1","update_at": "2018-06-04 12:14:39","season_name": "2015","competition_name": "Premier League"
    }
]

但我会返回这样的结果：

[
    {
        "team_id": "23291","seasons": [
                           ["season_name":"2017","season_id":"2"],["season_name":"2015","season_id":"3"],]
        "competition_name": "Premier League"
    }
]

如您所见，我的结果中有一行包含该seasons奖杯的array，作为，这更具可读性，并且避免了重复。

可以使用做到这一点sql吗？还是我需要解决php？

谢谢。

更新-表结构

CREATE TABLE IF NOT EXISTS `swp`.`competition` (
  `id` INT NOT NULL,`name` VARCHAR(255) NULL,PRIMARY KEY (`id`),ENGINE = InnoDB;


 CREATE TABLE IF NOT EXISTS `swp`.`competition_seasons` (
  `id` INT NOT NULL AUTO_INCREMENT,`competition_id` INT NOT NULL,`season_id` INT NULL,`name` VARCHAR(45) NOT NULL,`update_at` DATETIME NULL,INDEX `FK_competition_competition_seasons_competition_id_idx` (`competition_id` ASC),CONSTRAINT `FK_competition_competition_seasons_competition_id`
    FOREIGN KEY (`competition_id`)
    REFERENCES `swp`.`competition` (`id`)
    ON DELETE NO ACTION
    ON UPDATE NO ACTION)
ENGINE = InnoDB;


CREATE TABLE IF NOT EXISTS `swp`.`team_trophies` (
  `team_id` INT NOT NULL,`season_id` INT NOT NULL,`position` VARCHAR(255) NOT NULL,`wins` INT NOT NULL,INDEX `FK_team_team_trophies_team_id_idx` (`team_id` ASC),INDEX `FK_season_team_trophies_season_id_idx` (`season_id` ASC),CONSTRAINT `FK_team_team_trophies_team_id`
    FOREIGN KEY (`team_id`)
    REFERENCES `swp`.`team` (`id`)
    ON DELETE NO ACTION
    ON UPDATE NO ACTION,CONSTRAINT `FK_season_team_trophies_season_id`
    FOREIGN KEY (`season_id`)
    REFERENCES `swp`.`competition_seasons` (`id`)
    ON DELETE NO ACTION
    ON UPDATE NO ACTION)
ENGINE = InnoDB;


-- Some INSERTs

INSERT INTO `team_trophies` (`team_id`,`season_id`,`position`,`wins` VALUES (23291,2,'Winner',4),(23291,3,'Runner-up',1);


INSERT INTO `competition`  (`id`,`country_id`,`name`,`category`) VALUES (1093,1,'Premier League',1);

INSERT INTO `competition_seasons` (`id`,`competition_id`,`update_at`) VALUES
(1,1093,14963,'2018','2018-06-04 12:10:28'),(2,13198,'2017','2018-06-04 12:12:30');
sqlsql