单行的总和值? [英] Sum values of a single row?

问题描述

我有一个MySQL查询，该查询返回由1和0组成的单行.用于进度条指示器.我现在已在代码中对其求和，但是我尝试对查询中的值求和，并意识到我不能使用SUM()，因为它们有很多列，但只有一行.

I have a MySQL query that returns a single row that is a series of 1s and 0s. It's for a progress bar indicator. I have the summing of it in code now, but I tried to sum the values in a query, and realized I couldn't use SUM(), because they're many columns but just one row.

有没有一种方法可以自动在查询中求和?就像这样:

Is there a way I can sum this automatically in the query? It's like this:

item_1 | item_2 | item_3 | item_4
-------+--------+--------+--------
     1 |      1 |      0 |      0

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我忘了提及，item_1等不是简单的字段值，但是每个值都是一个表达式，例如SELECT IF( field_1 = 1 and field_2 IS NOT NULL, 0, 1 ) AS item_1 ...，所以看起来我必须做一个嵌套查询:

---

I forgot to mention, item_1 and so forth are not simple field values, but each is rather an expression, such as SELECT IF( field_1 = 1 and field_2 IS NOT NULL, 0, 1 ) AS item_1 ..., so it looks like I have to do a nested query:

SELECT ( item_1 + item_2 ... ) FROM ( SELECT IF( field_1 = y and field_2 IS NOT NULL, 1, 0 ) AS item_1 ... ) AS alias

正确吗?

推荐答案

select item_1 + item_2 + item_3 + item_4 as ItemSum
from MyTable

如果可以有空值，则需要按以下方式处理它们:

If there can be null values, you'll need to handle them like this:

select ifnull(item_1, 0) + ifnull(item_2, 0) + ifnull(item_3, 0) + ifnull(item_4, 0) as ItemSum
from MyTable

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