如何（MySQL）将组上的单元格值乘以？

Question

我需要在这样的查询中使用 MULTIPLY() 而不是 SUM() 操作所有值（简化）：

SELECT aav.id, COUNT(al.id_product) AS num_products, MULTIPLY(al.prop) AS mul_prop
FROM a_table a 
JOIN v_table aav ON a.id = aav.id_article AND a.fecha > '2020-01-13 11:28:54'
JOIN l_table al ON al.id_article = aav.id_article
JOIN l_table al2 ON al.id_article= al2.id_article AND al2.id_product = 113288
WHERE aav.id_attrib IN (SELECT a.id FROM attrib a WHERE a.key= 'my_key') 
GROUP BY id_article HAVING num_products > 2

我正在寻找一种轻量级的解决方案，无需创建视图或临时表，我只是在 OpenOffice 中寻找 MULTIPLY() 之类的函数。

我的目标是当存在一些 prop=0 的产品、一些负的 prop 产品或所有正的 prop 产品时，有负、正和零单元格，这是为了视觉目的。任何想法？我看到 MySQL 没有 MULTIPLY() 函数：/

Answer 1

我需要检查是否存在任何负（且不为零）、任何零或所有正属性

SELECT aav.id, 
       COUNT(al.id_product) AS num_products, 
       SUM(al.prop < 0) as count_negative, 
       SUM(al.prop = 0) as count_zeros,
       SUM(al.prop > 0) as count_positive
       -- the rest are NULL
FROM a_table a 
JOIN v_table aav ON a.id = aav.id_article AND a.fecha > '2020-01-13 11:28:54'
JOIN l_table al ON al.id_article = aav.id_article
JOIN l_table al2 ON al.id_article= al2.id_article AND al2.id_product = 113288
WHERE aav.id_attrib IN (SELECT a.id 
                        FROM attrib a 
                        WHERE a.key= 'my_key') 
GROUP BY id_article 
HAVING num_products > 2