在几个条件下计算总数 [英] Count total on couple of conditions

问题描述

假设我有一张这样的表:

Suppose I have a table like this:

id     col1     col2     col3
1      a        1        k1
2      a        2        k2
3      a        -3       k3
4      b        3        k4

现在，我想要'col1'与'id' = 1行中'col1'相同的所有行的'col2'列的总数.

Now, I want the total of column 'col2' for all rows where 'col1' is the same as 'col1' in the row where 'id' = 1.

所以这就是 1+2-3=0.

So that would be 1+2-3=0.

我将如何用 SQL 表达这一点?

How would I express this in SQL?

推荐答案

SELECT SUM(col2) from TABLE
where col1 in (SELECT col1 from TABLE where id = 1)

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