Pivot MySQL Table with Dynamic Columns

Question

I posted on an issue I was having before in representating data in a certain way and after 2 posts I was able to get enough information to realise what I need is a pivot table with dynamic columns.

I have been able to create a static pivot table with great effect but for serious reporting they are useless. Here is what I have done so far:

select `title` as `Payment Method`,
  sum(case when MONTH(t1.`month_payment`) = 1 then amount else 0 end) Jan,
  sum(case when MONTH(t1.`month_payment`) = 2 then amount else 0 end) Feb,
  sum(case when MONTH(t1.`month_payment`) = 3 then amount else 0 end) Mar,
  sum(case when MONTH(t1.`month_payment`) = 4 then amount else 0 end) Apr,
  sum(case when MONTH(t1.`month_payment`) = 5 then amount else 0 end) May,
  sum(case when MONTH(t1.`month_payment`) = 6 then amount else 0 end) Jun,
  sum(case when MONTH(t1.`month_payment`) = 7 then amount else 0 end) Jul,
  sum(case when MONTH(t1.`month_payment`) = 8 then amount else 0 end) Aug,
  sum(case when MONTH(t1.`month_payment`) = 9 then amount else 0 end) Sep,
  sum(case when MONTH(t1.`month_payment`) = 10 then amount else 0 end) Oct,
  sum(case when MONTH(t1.`month_payment`) = 11 then amount else 0 end) Nov,
  sum(case when MONTH(t1.`month_payment`) = 12 then amount else 0 end) `Dec`

from record_payment t1
join setting_payment_method ON
setting_payment_method.id = t1.method_id
where `month_payment` >= '$date_from'
  and `month_payment` <= '$date_to'
group by title with rollup

this is able to get me a static report from January to December but the issue is if the user searches from January 2015 to December 2017, the table will sum and aggregate Jan 2015, 2016 and 2017 all into the January that is displayed to the user which is wrong.

I have also produced a static pivot for yearly report:

select `title` as `Payment Method`,
  sum(case when YEAR(t1.`month_payment`) = 2013 then amount else 0 end) `2013`,
  sum(case when YEAR(t1.`month_payment`) = 2014 then amount else 0 end) `2014`,
  sum(case when YEAR(t1.`month_payment`) = 2015 then amount else 0 end) `2015`,
  sum(case when YEAR(t1.`month_payment`) = 2016 then amount else 0 end) `2016`,
  sum(case when YEAR(t1.`month_payment`) = 2017 then amount else 0 end) `2017`

from record_payment t1
join setting_payment_method ON
setting_payment_method.id = t1.method_id
where `month_payment` >= '$date_from'
  and `month_payment` <= '$date_to'
group by title with rollup

but sometimes you need reports that give you the breakdown of the year in months over a long period (eg 12+) so you can see a trend.

My attempt to do an automatic pivot was not so successful:

SET @sql = NULL;
SELECT
  GROUP_CONCAT(DISTINCT
    CONCAT(
      'sum(case when month_payment = ''',
      month_payment,
      ''' then amount end) AS `',
      month_payment,
      '`'
    )
  ) INTO @sql
FROM  record_payment;

SET @sql = CONCAT('SELECT `title` as `Payment Method`, ', @sql, ' FROM record_payment t1
join setting_payment_method ON
setting_payment_method.id = t1.method_id
where `month_payment` >= '$date_from'
  and `month_payment` <= '$date_to'
group by title with rollup');
PREPARE stmt FROM @sql;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;

Any help is appreciated.

Answer 1

I guess your month_payment column is a DATE (btw, should post the SHOW CREATE TABLE when you ask SQL questions so we don't have to guess).

But your first query is not formatting that to the year/month. Nor is it limiting the date range.

SELECT
  GROUP_CONCAT(DISTINCT
    CONCAT(
      'SUM(CASE WHEN EXTRACT(YEAR_MONTH FROM month_payment) = ',
      EXTRACT(YEAR_MONTH FROM month_payment),
      ' THEN AMOUNT END) AS `',
      EXTRACT(YEAR_MONTH FROM month_payment),
      '`'
    )
  ) INTO @sql
FROM record_payment
WHERE month_payment BETWEEN ? AND ?

See https://dev.mysql.com/doc/refman/5.7/en/date-and-time-functions.html#function_extract

---

Despite Barmar's suggestion, there's no reason to put this in a stored procedure. You tagged your question with PHP, and you can do this in PHP just fine:

<?php

...get a PDO connection...

$sql = "
    SELECT
      GROUP_CONCAT(DISTINCT
        CONCAT(
          'SUM(CASE WHEN EXTRACT(YEAR_MONTH FROM month_payment) = ',
          EXTRACT(YEAR_MONTH FROM month_payment),
          ' THEN AMOUNT END) AS `',
          EXTRACT(YEAR_MONTH FROM month_payment),
          '`'
        )
      ) AS `pivot_columns`
    FROM record_payment
    WHERE month_payment BETWEEN ? AND ?
";
$stmt = $pdo->prepare($sql);
$date_from = '2017-01-01';
$date_to   = '2017-08-01';
$stmt->execute([$date_from, $date_to]);
$row = $stmt->fetch();
$stmt->closeCursor();
$pivot_columns = $row['pivot_columns'];

$sql = "
    SELECT title AS `Payment Method`, {$pivot_columns}
    FROM record_payment t1
    JOIN setting_payment_method spm ON spm.id = t1.method_id
    WHERE month_payment BETWEEN ? AND ?
    GROUP BY title WITH ROLLUP
";
echo $sql;
$stmt = $pdo->prepare($sql);
$stmt->execute([$date_from, $date_to]);
$results = $stmt->fetchAll();
$stmt->closeCursor();

print_r($results);