使用MySql和PHP对公共日期下的数据进行分类

我试图建立一个项目管理系统，但我在尝试对共享同一日期的项目进行分类时遇到了困难。例如，如果我今天发布了两个项目，昨天发布了两个项目，我希望它显示如下：

2019-06-01:
project 1 
project 2
2019-05-31:
project 3
project 4

这是桌子的样子

------------------------------------------------
   id   |   project_name   |       date       |
   01   |   project 1      |    2019-06-01    |
   02   |   project 2      |    2019-06-01    |
   03   |   project 3      |    2019-05-31    |
   04   |   project 4      |    2019-05-31    |
------------------------------------------------

这是我的代码：

---

考虑以下几点：

dll:

DROP TABLE my_table;

CREATE TABLE my_table
(id SERIAL PRIMARY KEY
,project_name VARCHAR(12) NOT NULL
,date DATE NOT NULL
);

INSERT INTO my_table VALUES
(1,'project 1','2019-06-01'),
(2,'project 2','2019-06-01'),
(3,'project 3','2019-05-31'),
(4,'project 4','2019-05-31');

Array
(
    [2019-06-01] => Array
        (
            [0] => project 1
            [1] => project 2
        )

    [2019-05-31] => Array
        (
            [0] => project 3
            [1] => project 4
        )

)

代码

<?php

include('path/to/connection/stateme.nts');

$query = "
SELECT date
     , project_name
  FROM my_table
 ORDER
    BY date DESC
     , project_name; -- ORDER BY is not strictly necessary, as the ordering can be done in presentation code.
";

$result = mysqli_query($conn,$query);

$array = array();

while($row = mysqli_fetch_assoc($result)){
  $array[] = $row;
}

$new_array = array();

foreach($array as $v){
  $new_array[$v['date']][] = $v['project_name'];
}

print_r($new_array);
?>

显然，您可以使用PDO方法摆脱第一个查询。在第二个查询中删除groupby和date内容。只需选择所需的行，并在PHP.nice explaution@草莓中处理所有其他内容
Array
(
    [2019-06-01] => Array
        (
            [0] => project 1
            [1] => project 2
        )

    [2019-05-31] => Array
        (
            [0] => project 3
            [1] => project 4
        )

)