所以我试图获得年复一年的数据。虽然我可以做这样的事情
SELECT tbl_products.product_name, SUM(tbl_invoice_details.quantity- IFNULL(tbl_invoice_details.quantity_returned,0)),
MONTH(tbl_invoice.invoice_date) as `month`, sort_order
FROM
tbl_invoice_details
INNER JOIN tbl_invoice ON tbl_invoice_details.invoice_ID = tbl_invoice.invoice_ID
INNER JOIN tbl_products ON tbl_products.product_ID = tbl_invoice_details.product_ID
WHERE tbl_invoice.invoice_date BETWEEN '2016-01-01' AND '2016-07-01'
GROUP BY `month`, product_name, sort_order
order by `month`, sort_order
并运行两次（每年一次）。但是，如果有一年销售的产品而另一年没有销售，那么在创建图表时会出现问题。我可以在后端的代码中修复它，但似乎会浪费很多周期。我也可以在两年内对产品进行select distinct，并在后端使用该结果对每个产品运行查询，但这将是大量的数据库调用。有谁知道在mySql中更好的方法吗？
答案 0 :(得分：0)
如果我理解正确，您可以更改where子句：
SELECT p.product_name, SUM(id.quantity - IFNULL(id.quantity_returned,0)),
YEAR(i.invoice_date) as ayyyy, MONTH(i.invoice_date) as `month`, sort_order
FROM tbl_invoice_details id INNER JOIN
tbl_invoice i
ON id.invoice_ID = i.invoice_ID INNER JOIN
tbl_products p
ON p.product_ID = id.product_ID
WHERE month(i.invoice_date) IN (1, 2, 3, 4, 5, 6) AND
year(i.invoice_date) IN (2015, 2016)
GROUP BY YEAR(i.invoice_date), `month`, product_name, sort_order
ORDER BY yyyy, `month`, sort_order;
编辑：
您可能希望为这些值添加两列：
SELECT p.product_name,
SUM(CASE WHEN YEAR(i.voice_date) = 2015 THEN id.quantity - COALESCE(id.quantity_returned, 0) END) as val_2015,
SUM(CASE WHEN YEAR(i.voice_date) = 2016 THEN id.quantity - COALESCE(id.quantity_returned, 0) END) as val_2016,
MONTH(i.invoice_date) as `month`, sort_order
FROM tbl_invoice_details id INNER JOIN
tbl_invoice i
ON id.invoice_ID = i.invoice_ID INNER JOIN
tbl_products p
ON p.product_ID = id.product_ID
WHERE month(i.invoice_date) IN (1, 2, 3, 4, 5, 6) AND
year(i.invoice_date) IN (2015, 2016)
GROUP BY YEAR(i.invoice_date), `month`, product_name, sort_order
ORDER BY yyyy, `month`, sort_order;
答案 1 :(得分：0)
如果您没有日期表并且无法创建日期表，那么一堆工会可能会有所帮助。例如
/*
DROP TABLE TBL_PRODUCTS;
CREATE TABLE TBL_PRODUCTS(PRODUCT_ID INT,PRODUCT_NAME VARCHAR(10));
INSERT INTO TBL_PRODUCTS VALUES
(1,'ABC'), (2,'DEF');
CREATE TABLE TBL_INVOICE(INVOICE_ID INT,INVOICE_DATE DATE);
INSERT INTO TBL_INVOICE VALUES
(1,'2015-06-01'), (2,'2015-07-01'),(3,'2015-08-01'),
(4,'2016-01-01'), (5,'2016-02-01'),(6,'2016-03-01');
DROP TABLE TBL_INVOICE_DETAILS;
CREATE TABLE TBL_INVOICE_DETAILS (INVOICE_ID INT,PRODUCT_ID INT,QUANTITY INT,QUANTITY_RETURNED INT);
INSERT INTO TBL_INVOICE_DETAILS VALUES
(1,1,10,NULL), (2,1,10,NULL),(3,2,10,NULL),
(4,1,10,NULL), (5,1,10,NULL),(6,2,10,NULL);
*/
USE SANDBOX;
SELECT S.product_name, SUM(S.quantity - IFNULL(S.quantity_returned,0)) NET,
S.yyyy, S.`month`
FROM
(
SELECT p.product_name, id.quantity ,id.quantity_returned,
YEAR(i.invoice_date) as yyyy, MONTH(i.invoice_date) as `month`
FROM tbl_invoice_details id
INNER JOIN tbl_invoice i ON id.invoice_ID = i.invoice_ID
INNER JOIN tbl_products p ON p.product_ID = id.product_ID
UNION SELECT P.PRODUCT_NAME,0,0,2015,1 FROM TBL_PRODUCTS P
UNION SELECT P.PRODUCT_NAME,0,0,2015,2 FROM TBL_PRODUCTS P
UNION SELECT P.PRODUCT_NAME,0,0,2015,3 FROM TBL_PRODUCTS P
UNION SELECT P.PRODUCT_NAME,0,0,2015,4 FROM TBL_PRODUCTS P
UNION SELECT P.PRODUCT_NAME,0,0,2015,5 FROM TBL_PRODUCTS P
UNION SELECT P.PRODUCT_NAME,0,0,2015,6 FROM TBL_PRODUCTS P
UNION SELECT P.PRODUCT_NAME,0,0,2015,7 FROM TBL_PRODUCTS P
UNION SELECT P.PRODUCT_NAME,0,0,2015,8 FROM TBL_PRODUCTS P
UNION SELECT P.PRODUCT_NAME,0,0,2015,9 FROM TBL_PRODUCTS P
UNION SELECT P.PRODUCT_NAME,0,0,2015,10 FROM TBL_PRODUCTS P
UNION SELECT P.PRODUCT_NAME,0,0,2015,11 FROM TBL_PRODUCTS P
UNION SELECT P.PRODUCT_NAME,0,0,2015,12 FROM TBL_PRODUCTS P
UNION SELECT P.PRODUCT_NAME,0,0,2016,1 FROM TBL_PRODUCTS P
UNION SELECT P.PRODUCT_NAME,0,0,2016,2 FROM TBL_PRODUCTS P
UNION SELECT P.PRODUCT_NAME,0,0,2016,3 FROM TBL_PRODUCTS P
UNION SELECT P.PRODUCT_NAME,0,0,2016,4 FROM TBL_PRODUCTS P
UNION SELECT P.PRODUCT_NAME,0,0,2016,5 FROM TBL_PRODUCTS P
UNION SELECT P.PRODUCT_NAME,0,0,2016,6 FROM TBL_PRODUCTS P
UNION SELECT P.PRODUCT_NAME,0,0,2016,7 FROM TBL_PRODUCTS P
UNION SELECT P.PRODUCT_NAME,0,0,2016,8 FROM TBL_PRODUCTS P
UNION SELECT P.PRODUCT_NAME,0,0,2016,9 FROM TBL_PRODUCTS P
UNION SELECT P.PRODUCT_NAME,0,0,2016,10 FROM TBL_PRODUCTS P
UNION SELECT P.PRODUCT_NAME,0,0,2016,11 FROM TBL_PRODUCTS P
UNION SELECT P.PRODUCT_NAME,0,0,2016,12 FROM TBL_PRODUCTS P
) S
WHERE S.YYYY IN (2015,2016)
GROUP BY S.PRODUCT_NAME,S.YYYY,S.`MONTH`
，即使没有像这样的发票，也会为每个月的每件商品返回结果集
+--------------+------+------+-------+
| product_name | NET | yyyy | month |
+--------------+------+------+-------+
| ABC | 0 | 2015 | 1 |
| ABC | 0 | 2015 | 2 |
| ABC | 0 | 2015 | 3 |
| ABC | 0 | 2015 | 4 |
| ABC | 0 | 2015 | 5 |
| ABC | 10 | 2015 | 6 |
| ABC | 10 | 2015 | 7 |
| ABC | 0 | 2015 | 8 |
| ABC | 0 | 2015 | 9 |
| ABC | 0 | 2015 | 10 |
| ABC | 0 | 2015 | 11 |
| ABC | 0 | 2015 | 12 |
| ABC | 10 | 2016 | 1 |
| ABC | 10 | 2016 | 2 |
| ABC | 0 | 2016 | 3 |
| ABC | 0 | 2016 | 4 |
| ABC | 0 | 2016 | 5 |
| ABC | 0 | 2016 | 6 |
| ABC | 0 | 2016 | 7 |
| ABC | 0 | 2016 | 8 |
| ABC | 0 | 2016 | 9 |
| ABC | 0 | 2016 | 10 |
| ABC | 0 | 2016 | 11 |
| ABC | 0 | 2016 | 12 |
| DEF | 0 | 2015 | 1 |
| DEF | 0 | 2015 | 2 |
| DEF | 0 | 2015 | 3 |
| DEF | 0 | 2015 | 4 |
| DEF | 0 | 2015 | 5 |
| DEF | 0 | 2015 | 6 |
| DEF | 0 | 2015 | 7 |
| DEF | 10 | 2015 | 8 |
| DEF | 0 | 2015 | 9 |
| DEF | 0 | 2015 | 10 |
| DEF | 0 | 2015 | 11 |
| DEF | 0 | 2015 | 12 |
| DEF | 0 | 2016 | 1 |
| DEF | 0 | 2016 | 2 |
| DEF | 10 | 2016 | 3 |
| DEF | 0 | 2016 | 4 |
| DEF | 0 | 2016 | 5 |
| DEF | 0 | 2016 | 6 |
| DEF | 0 | 2016 | 7 |
| DEF | 0 | 2016 | 8 |
| DEF | 0 | 2016 | 9 |
| DEF | 0 | 2016 | 10 |
| DEF | 0 | 2016 | 11 |
| DEF | 0 | 2016 | 12 |
+--------------+------+------+-------+
48 rows in set (0.02 sec)