php - 如何编写此 mySQL 查询以在每一列中显示多个数据？

Question

我的mySQL表如下

id - hash - page - timestamp
1 - ig35sdf89 - page1 - 2015-05-06 12:03:54
2 - ig35sdf89 - page2 - 2015-05-06 12:06:54
3 - ig35sdf89 - page1 - 2015-05-06 12:08:54
4 - xgd98rgf - page1 - 2015-05-06 12:10:54
5 - aaaat43gr - page3 - 2015-05-06 12:12:54

我的问题是要使用什么 mySQL 查询来显示类似我将通过时间戳显示每个哈希顺序路径的位置:

ig35sdf89  - page1 - 2015-05-06 12:08:54
           - page2 - 2015-05-06 12:03:54
           - page1 - 2015-05-06 12:06:54

xgd98rgf  - page1 - 2015-05-06 12:10:54

aaaat43gr  - page3 - 2015-05-06 12:12:54

我正在使用 PHP。

Answer 1

mysql 支持 group_concat 。哪个正好支持这个用例

所以如果你的表定义为

表定义

create table pages
(
  id integer auto_increment primary key not null,
  hash varchar(10) not null,
  pagename varchar(128) not null,
  last_access_time timestamp not null
);

你可以用这个

查询

select 
hash, group_concat(pagename, last_access_time SEPARATOR ';\n')
from
pages
group by hash
;

或者可以返回 json 以与 php json_decode 一起使用:

查询输出json

select 
concat('{', prty_hash, ',"pages":[', group_concat(json_page SEPARATOR ','), ']}') as json_prt
from
(
select 
concat('"hash":"', hash, '"') as prty_hash,
concat('"page":', pagename) as prty_pagename,
concat('{', '"page":"', pagename, '",', '"last_access_time":"', last_access_time, '"}') as json_page
from
pages
) prty
group by prty_hash
;

这给出了

json输出

{"hash":"123456789","pages":[{"page":"mypage3","last_access_time":"2015-05-06 09:34:02"},{"page":"mypage2","last_access_time":"2015-05-06 09:34:02"},{"page":"mypage1","last_access_time":"2015-05-06 09:34:02"}]}

{"hash":"999999","pages":[{"page":"mypage4","last_access_time":"2015-05-06 09:34:02"}]}

链接到 sqlfiddle

这现在可以在 php 中使用，例如:

php

<?php

$servername = "localhost";
$username = ...;
$password = ...;
$dbname = ...;

// Create connection
$conn = new mysqli($servername, $username, $password, $dbname);

// GET
if ($_SERVER['REQUEST_METHOD'] == "GET")
{
    // Create connection
    $conn = new mysqli($servername, $username, $password, $dbname);

    // Check connection
    if ($conn->connect_error) {
        die("Connection failed: " . $conn->connect_error);
     } 

    $sql = <<<heredoc
      select 
      concat('{', prty_hash, ',"pages":[', group_concat(json_page SEPARATOR ','), ']}') as json_prt
      from
      (
        select 
        concat('"hash":"', hash, '"') as prty_hash,
        concat('"page":', pagename) as prty_pagename,
        concat('{', '"page":"', pagename, '",',       '"last_access_time":"', last_access_time, '"}') as json_page
        from
        pages
      ) prty
      group by prty_hash
      ;
heredoc;

    $dbResult = $conn->query($sql);
    $appResult = array();

    while($row = $dbResult->fetch_assoc()) {
        $json_res_obj = json_decode($row['json_prt']);  
        // do something with the object, render/echo it on the page etc..
    }

    $conn->close();
}
else
{
    die("Invalid request");
}


?>

注意:未经测试的 php..