在sql中乘以2行 [英] Multiply 2 rows in sql

问题描述

我正在尝试创建一个 SQL 查询，我将 1 行的值乘以其下方行中的列中的值.我该怎么做?两列相乘很容易，但我似乎坚持将两行相乘.

Hi I am trying to create a SQL query were I multiply the values of 1 row by the values in its column in the row beneath it. How can I do it? multiplying two columns is easy but i seem stuck on multiplying 2 rows.

推荐答案

这取决于你的情况.

简单来说......如果你的桌子看起来像这样......

To simplyfy it... if your table looks like this...

CREATE TABLE `test` (
  `number` BIGINT(20) NOT NULL,
  PRIMARY KEY (`number`)
) ENGINE=INNODB DEFAULT CHARSET=latin1

...还有一些像这样的数据...

... and some data in it like this...

number
------
     2
     3
     4

...你可以这样做:

SELECT 
  (SELECT number 
  FROM test 
  WHERE number = 2) * 
  (SELECT number 
  FROM test 
  WHERE number = 3) AS "product" 
FROM test 
LIMIT 1;

您也可以将表JOIN 连接到其自身上.

You might aswell just JOIN the table onto itself.

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