如何避免包含null或零值的列

Question

我想避免那些包含null或零值的列

这里是表结构

- 表orders

的表结构

CREATE TABLE `orders` (
  `id` int(11) NOT NULL,
  `customer_id` int(11) NOT NULL,
  `restaurant_id` int(11) NOT NULL,
  `source_id` int(1) NOT NULL,
  `purchase_method` varchar(255) NOT NULL,
  `total_price` int(11) NOT NULL,
  `date_created` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

--
-- Dumping data for table `orders`
--

INSERT INTO `orders` (`id`, `customer_id`, `restaurant_id`, `source_id`, `purchase_method`, `total_price`, `date_created`) VALUES
(1, 1, 1, 3, 'Cash', 500, '2016-05-31 11:44:16'),
(2, 1, 1, 3, 'Cash', 1500, '2016-06-01 11:44:22'),
(3, 1, 1, 3, '', 650, '2016-06-02 11:44:26'),
(4, 1, 1, 2, 'cash', 1500, '2016-06-03 11:44:31'),
(5, 1, 1, 1, 'cash', 12000, '2016-06-04 21:08:00'),
(6, 1, 1, 1, 'cash', 14500, '2016-06-05 00:00:00'),
(7, 1, 1, 2, 'cash', 15000, '2016-06-10 09:47:15'),
(8, 1, 1, 2, 'cash', 14500, '2016-05-10 10:03:55'),
(9, 1, 1, 1, 'cash', 11800, '2016-06-08 00:00:00'),
(10, 1, 1, 2, 'ss', 300, '2016-06-08 01:06:56'),
(11, 1, 1, 1, 'online', 400, '2016-05-10 10:03:20'),
(12, 1, 1, 3, 'cash', 5000, '2016-06-09 06:23:16'),
(13, 1, 1, 2, 'cash', 2000, '2016-05-10 10:03:35'),
(14, 1, 1, 1, 'cash', 499, '2016-04-11 18:30:00'),
(15, 1, 1, 1, 'cash', 2010, '2016-03-11 18:58:00'),
(16, 1, 1, 1, 'cash', 599, '2016-03-11 18:30:00'),
(17, 1, 1, 1, 'online', 699, '2016-05-02 18:30:00');

-- --------------------------------------------------------

the query I tried below it


SELECT 
  SUM(CASE WHEN MONTH(date_created)=1 THEN (total_price) END) Jan,
  SUM(CASE WHEN MONTH(date_created)=2 THEN (total_price) END) Feb,
  SUM(CASE WHEN MONTH(date_created)=3 THEN (total_price) END) Mar,
  SUM(CASE WHEN MONTH(date_created)=4 THEN (total_price) END)  Apr,
  SUM(CASE WHEN MONTH(date_created)=5 THEN (total_price) END) May,
  SUM(CASE WHEN MONTH(date_created)=6 THEN (total_price) END) Jun,
  SUM(CASE WHEN MONTH(date_created)=7 THEN (total_price) END)  July,
  SUM(CASE WHEN MONTH(date_created)=8 THEN (total_price) END) Aug,
  SUM(CASE WHEN MONTH(date_created)=9 THEN (total_price) END) Sep,
  SUM(CASE WHEN MONTH(date_created)=10 THEN (total_price) END) 'Oct',
  SUM(CASE WHEN MONTH(date_created)=11 THEN (total_price) END) Nov,
  SUM(CASE WHEN MONTH(date_created)=12 THEN (total_price) END) 'Dec'
FROM orders
WHERE source_id =1 AND  date_created BETWEEN(CURDATE() - INTERVAL 1 MONTH)
    AND CURDATE()

我从查询

获得的结果

Jan    Feb  Mar  Apr    May   Jun   July    Aug  Sep    Oct  Nov   Dec
null   null null null   null  38300 null null null null null null  null

欲望结果

 may june 
 0    38300

Answer 1

SQL查询返回一组固定的列，由from子句确定。如果需要一组变量列，则可以使用动态SQL。

在您的情况下，也许将结果作为列就足够了：

select month(date_created), sum(total_price)
from orders
where source_id = 1 and
      date_created BETWEEN(CURDATE() - INTERVAL 1 MONTH) and CURDATE()
group by month(date_created)
having sum(total_price) <> 0;