我很难从12月(上个月的第3月开始的任何时间)获取行。我正在尝试计算在一定时期内销售的产品数量。这是我当前的查询:
SELECT
a.id,
a.default_code,
(
SELECT SUM(product_uom_qty)
AS
"Total Sold"
FROM
sale_order_line c
WHERE
c.product_id = a.id
),
(
SELECT SUM(product_uom_qty)
AS
"Month 3"
FROM sale_order_line c
WHERE
c.product_id = a.id
AND
MONTH(c.create_date) = MONTH(CURRENT_DATE - INTERVAL '3 Months')
AND
YEAR(c.create_date) = YEAR(CURRENT_DATE - INTERVAL '3 Months')
)
FROM
product_product a
这是数据库的样子:
sale_order_line
product_id product_uom_qty create_date
33 230 2014-07-01 16:47:45.294313
product_product
id default_code
33 WHDXEB33
这是我收到的错误:
ERROR: function month(timestamp without time zone) does not exist LINE 21: MONTH(c.create_date) = MONTH(CURRENT_DATE - INTERVAL
有什么帮助我指出正确的方向吗?
使用date_trunc()计算时间戳记范围:
SELECT id, default_code
, (SELECT SUM(product_uom_qty)
FROM sale_order_line c
WHERE c.product_id = a.id
) AS "Total Sold"
, (SELECT SUM(product_uom_qty)
FROM sale_order_line c
WHERE c.product_id = a.id
AND c.create_date >= date_trunc('month', now()) - interval '2 month'
AND c.create_date < date_trunc('month', now()) - interval '1 month'
) AS "Month 3"
FROM product_product a;
要获得十二月(现在是二月),请使用以下表达式:
AND c.create_date >= date_trunc('month', now()) - interval '2 month'
AND c.create_date < date_trunc('month', now()) - interval '1 month'
date_trunc('month', now())
产生'2015-02-01 00:00',减去2个月后,您得到'2014-12-01 00:00'。因此,“ 3个月”可能是骗人的。
另外,请确保使用如所示的可扩展表达式,以提高性能并允许使用索引。
根据您实际的数据库设计和数据分配,这可能会更快:
SELECT a.id, a.default_code, c."Total Sold", c."Month 3"
FROM product_product a
LEFT JOIN (
SELECT product_id AS id
, SUM(product_uom_qty) AS "Total Sold"
, SUM(CASE WHEN c.create_date >= date_trunc('month', now()) - interval '2 month'
AND c.create_date < date_trunc('month', now()) - interval '1 month'
THEN product_uom_qty ELSE 0 END) AS "Month 3"
FROM sale_order_line
GROUP BY 1
) c USING (id);
由于选择了所有行,因此这可能比相关子查询快。虽然是吧,总之前你的加盟,这是更便宜,但。
当选择单个或几个产品,这实际上可能较慢,但!比较:
或者使用FILTER
Postgres 9.4+中的子句:
...
, SUM(product_uom_qty)
FILTER (WHERE c.create_date >= date_trunc('month', now()) - interval '2 month'
AND c.create_date < date_trunc('month', now()) - interval '1 month'
) AS "Month 3"
...
细节:
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