MYSQL groupb函数中的条件输出

Question

所以我有一个表格

    +----+-----+
    | id | Val |
    +----+-----+
    |  1 |  20 |
    |  1 |  30 |
    |  2 |   0 |
    |  2 |  80 |
    |  3 |  45 |
    |  3 |  60 |
    |  4 |   0 |
    |  4 |  30 |
    +----+-----+

我想对id列和Val列中的值进行分组。仅，如果其中一个值为零，则结果总和也应为零

对于上表，输出将是

    +----+-------+
    | id |SumVal |
    +----+-------+
    |  1 |  50   |
    |  2 |   0   |
    |  3 | 105   |
    |  4 |   0   |
    +----+-------+

我尝试在sum函数中使用条件语句（CASE和IF），但这些条件似乎只适用于各个元素。

任何指针？

Answer 1

使用SUM和IF：

SELECT id, (SUM(val) * IF(val = 0, 0, 1)) AS SumVal FROM idval GROUP BY id;

Answer 2

检查此简单查询。

        select id ,SUM(val)
        from #Table
        where val=0
        group by ID 
        union
        select id ,SUM(val)
        from #Table
        where id not in (select id from #Table where val=0)
        group by ID 

  

OutPut：

Answer 3

试试这个

select id,if(cast(val as signed),sum(val),0) as total from tbl_name group by id;