MySQL 8.0

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CREATE TABLE `companies` (
  `id` int(10) unsigned NOT NULL AUTO_INCREMENT,
  `code` varchar(255) COLLATE utf8mb4_unicode_ci NOT NULL,
  `name` varchar(255) COLLATE utf8mb4_unicode_ci NOT NULL,
  `is_marked` tinyint(4) DEFAULT NULL,
  `created_at` timestamp NULL DEFAULT NULL,
  `updated_at` timestamp NULL DEFAULT NULL,
  PRIMARY KEY (`id`),
  UNIQUE KEY `companies_code_unique` (`code`)
) 
 
CREATE TABLE `reports` (
  `id` int(10) unsigned NOT NULL AUTO_INCREMENT,
  `company_id` int(10) unsigned NOT NULL,
  `quarter` varchar(255) COLLATE utf8mb4_unicode_ci NOT NULL,
  `fiscal_year` int(11) NOT NULL,
  `revenue` decimal(12,2) DEFAULT NULL,
  `taxes` decimal(10,2) DEFAULT NULL,
  `employees` int(11) DEFAULT NULL,
  `created_at` timestamp NULL DEFAULT NULL,
  `updated_at` timestamp NULL DEFAULT NULL,
  PRIMARY KEY (`id`),
  KEY `reports_company_id_foreign` (`company_id`),
  CONSTRAINT `reports_company_id_foreign` FOREIGN KEY (`company_id`) REFERENCES `companies` (`id`) ON DELETE CASCADE
)
INSERT INTO `companies` (`code`, `name`, `is_marked`, `created_at`, `updated_at`) VALUES ('123456', 'ABC INC', 1, '2018-09-21 13:32:03', '2018-09-21 13:32:03')
 , ('987654', 'XYZ LLC', 1, '2018-09-20 13:32:03', '2018-09-20 13:32:03');


Records: 2  Duplicates: 0  Warnings: 0


INSERT INTO `reports` (`company_id`, `quarter`, `fiscal_year`, `revenue`, `taxes`, `employees`, `created_at`, `updated_at`)
  VALUES (1, 'Q2', 2018, 11056.00, 35000.86, 568, '2018-09-21 13:32:03', '2018-09-21 13:32:03'),
  (1, 'Q1', 2018, 5000.00, 45000.86, 600, '2018-09-22 13:32:03', '2018-09-22 13:32:03');


Records: 2  Duplicates: 0  Warnings: 0


INSERT INTO `reports` (`company_id`, `quarter`, `fiscal_year`, `revenue`, `taxes`, `employees`, `created_at`, `updated_at`)
  VALUES (2, 'Q2', 2018, 5000.00, NULL, 10, '2018-09-22 13:32:03', '2018-09-22 13:32:03'), (2, 'Q1', 2018, NULL, 45000.86, 5, '2018-09-22 13:32:03', '2018-09-22 13:32:03');

Records: 2  Duplicates: 0  Warnings: 0


SELECT 
	c.name, r.quarter, r.fiscal_year, r.revenue, r.taxes, r.employees
FROM companies c
JOIN reports r 
ON r.company_id = c.id


name
quarter
fiscal_year
revenue
taxes
employees


ABC INC
Q2
2018
11056.00
35000.86
568

ABC INC
Q1
2018
5000.00
45000.86
600

XYZ LLC
Q2
2018
5000.00
null
10

XYZ LLC
Q1
2018
null
45000.86
5


WITH cte AS (
  SELECT c.name, quarter, fiscal_year
   ,revenue, 100*(revenue-LAG(revenue) OVER s)/NULLIF(revenue,0) AS change_revenue
   ,taxes ,100*(taxes-LAG(taxes) OVER s)/NULLIF(taxes,0) AS change_taxes
   ,employees ,employees-LAG(employees) OVER s AS change_employees
  FROM companies c
  JOIN reports r ON r.company_id = c.id
  WINDOW s AS (PARTITION BY company_id ORDER BY quarter)
)
SELECT *
FROM cte
WHERE quarter = 'Q2';


name
quarter
fiscal_year
revenue
change_revenue
taxes
change_taxes
employees
change_employees


ABC INC
Q2
2018
11056.00
54.775687
35000.86
-28.570727
568
-32

XYZ LLC
Q2
2018
5000.00
null
null
null
10
5
name	quarter	fiscal_year	revenue	taxes	employees
ABC INC	Q2	2018	11056.00	35000.86	568
ABC INC	Q1	2018	5000.00	45000.86	600
XYZ LLC	Q2	2018	5000.00	null	10
XYZ LLC	Q1	2018	null	45000.86	5