uksort help - 在单个需要帮助时使用 GROUP BY

Question

Hello I have an array that looks like this after passing it through uksort()

    Array
(
    [3] => Array
        (
            [job_id] => 4
            [job_title] => Supercar Test Driver
            [company_name] => McLaren
            [logo_small] => small_mclaren001.png
            [logo_large] => large_mclaren002.png
            [employer_id] => 3
        )

    [2] => Array
        (
            [job_id] => 3
            [job_title] => Recruitment Consultant - Driving
            [company_name] => MoovJob.com
            [logo_small] => small_rac001.png
            [logo_large] => large_rac002.png
            [employer_id] => 2
        )

    [1] => Array
        (
            [job_id] => 5
            [job_title] => Postal Worker / Post Person
            [company_name] => Royal Mail
            [logo_small] => small_royalmail001.png
            [logo_large] => large_royalmail002.png
            [employer_id] => 4
        )

    [0] => Array
        (
            [job_id] => 6
            [job_title] => Another Job
            [company_name] => MoovJob.com
            [logo_small] => small_rac001.png
            [logo_large] => large_rac002.png
            [employer_id] => 2
        )

)

However if in my SQL that returns this array I add GROUP BY company_name the final entry in the array dissapears, what I am trying to achieve is to place the job title under the company name, but only show the company name once, something similar to this,

Company Name 1
Job Title 1 Job Title 2 Job Title 3

Company Name 2
Job Title 4

Company Name
Job Title 5 Job Title 6

I am trying to achieve this, by doing the followng in my view, however I can only show one vacancy, what am I doing wrong?

    <?php $oldemp   = "";?>
<?php foreach($jobs as $key => $value) : ?>
   <?php if ($oldemp != $value['company_name']) : ?>
        <?php $oldemp = $value['company_name']; ?>
        <section class="employer">
            <div class="job_holder">
                <img src="<?php echo base_url(); ?>media/uploads/users/<?php echo $value['logo_large']; ?>" width="198" height="148" alt="<?php echo $value['company_name']; ?>"/>
                <dl>
                    <dt><?php echo count($key); ?></dt>
                    <dd>Matches</dd>
                </dl>
    <?php endif;?>
            <span> + <a href="/jobwall/getjob/<?php echo $value['job_id']; ?>"><?php echo $value['job_title']; ?></a></span>
            </div>
        </section>
<?php endforeach; ?>


    function jobcmp($job1, $job2)
    {
        return strcmp($job1['company_name'], $job2['company_name']);
    }

Answer 1

Although it would be possible to display the data using your approach I normally find it much more straightforward to create a second array in a more convenient format:

$groupedJobs = array();
foreach ($jobs as $data) {
    if (!isset($groupedJobs[$data['company_name']])) {
        $groupedJobs[$data['company_name']] = array();
    }
    $groupedJobs[$data['company_name']][] = $data;
}

this creates a new array using the company name as the key and that company's jobs in a nested array as the value, giving you something like this:

['MoovJob.com'] => Array
    (
        [0] => Array
            (
                (job data)
            ),
        [1] => Array 
            (
                (etc.)
            )
    ),
['McLaren'] = Array
    (
        (etc)
    )

it is then much easier to loop through this array and display:

foreach ($groupedJobs as $companyName => $jobs) {
    echo $companyName;
    foreach ($jobs as $job) {
        echo $job['job_title'].'<br />';
    }
}

Answer 2

It looks like the array is sorted by job_title DESC when it should be sorted by company_name

Answer 3

Your array is not sorted correctly, employees with the same id should be one after another, for this array you should use usort method like this

usort($jobs, function($a, $b) {
 if($a['employee_id'] == $b['employee_id'] return 0;
 return ($a['employee_id'] < $b['employee_id']) ? 1 : -1;
})

The other way and I think the better one for your purpose is to use array_walk to prepare data for this section loop. Method below will remove duplicates from the table and join all job_titles for the same employees in a one key in primary employee record.

array_walk($jobs, function($emp, $index) use(&jobs) {
  static $primary;

  if(isset($primary[$emp['employee_id']) {
    $jobs[$primary[$emp['employee_id']]]['job_titles'][$emp['job_id'] = $emp['job_title'];
    unset($jobs[$index]);
  } else {
    $primary[$emp['employee_id']] = $index; //remeber index of primary entry
  }
});

Answer 4

It would help if you showed the SQL query. However, the row that disappears is obviously related to the GROUP BY company_name you add.

When you add a GROUP BY groupfield , all rows with same groupfield "collapse" into one row. The columns that depend on that field, like company_logo can usually safely stay in the SELECT list. All others should be removed or changed to use an aggregate function like SUM() or COUNT() .

So, if you want to show numbers of jobs for every company, use COUNT(job_id) or COUNT(*) .

In your case, you have two options I think.

• First option is to NOT use GROUP BY , perhaps only ORDER BY and use PHP code to show what you need.

• Second option is to use GROUP BY and the aggregate GROUP_CONCAT() function.

You can use it like:

SELECT
    company_name
  , GROUP_CONCAT( job_id
                  ORDER BY job_id
                  SEPARATOR ', ' )
      AS job_ids
  , GROUP_CONCAT( job_title
                  ORDER BY job_id
                  SEPARATOR ', ' )
      AS job_titles
  , GROUP_CONCAT( CONCAT(job_id, '-', job_title)
                  ORDER BY job_id
                  SEPARATOR ', ' )
      AS job_ids_and_titles
  , company_name
  , logo_small
  , logo_large
  , employer_id
FROM 
  ...
GROUP BY company_name