Question

DB-Fiddle:

CREATE TABLE operations (
    id int auto_increment primary key,
    time_stamp DATE,
    product VARCHAR(255),
    quantity INT
);

INSERT INTO operations
(time_stamp, product, quantity
)
VALUES 
("2020-01-01", "Product_A", "600"),
("2020-01-01", "Product_B", "400"),
("2020-01-01", "Product_C", "700"),
("2020-03-15", "Product_A", "300"),
("2020-03-15", "Product_B", "500"),
("2020-03-15", "Product_C", "900"),
("2020-03-15", "Product_D", "150");

预期结果：

Product           2020-01-01       2020-03-15       difference
Product_A             600              300             -300
Product_B             400              500              100
Product_C             700              900              200 
Product_D               0              150              150

在以上结果中，我想显示每个quantity的每种产品的time_stamp，并在列difference的{{1}}之间计算quantities。

到目前为止，我想出了类似的方法，但无法使其起作用：

difference

您是否知道我需要更改查询以实现预期结果？

Answer 1

您可以进行条件聚合：

select
    product,
    sum(case when time_stamp = '2020-01-01' then quantity else 0 end) quanty_20200101,
    sum(case when time_stamp = '2020-03-15' then quantity else 0 end) quanty_20200315,
    sum(case when time_stamp = '2020-03-15' then quantity else -quantity end) diff
from operations 
where time_stamp in ('2020-01-01', '2020-03-15')
group by product

比较两个时间戳的值并计算差异

1 个答案: