Question

我有一个可以容纳6个值的列（1,2,3，A，B，C）

我可以数（*）他们看起来像这样

select mycol, count(*) as ttl from mytable group by mycol;
    mycol  ttl
    1       46
    2       53
    3       10
    A       5 
    B       4
    C       2

但是我想要将1和As，以及2和B这样的总和相加

mycol total
var1    51
var2    57
var3    12

案例陈述会为此工作吗？像案例1或A那样对待它们

Answer 1

是的，case声明适用于此：

select (case when mycol in ('1', 'var1') then 'var1'
             when mycol in ('2', 'var2') then 'var2'
             when mycol in ('3', 'var3') then 'var3'
        end),
       sum(ttl) as Total
from mytable t
group by (case when mycol in ('1', 'var1') then 'var1'
               when mycol in ('2', 'var2') then 'var2'
               when mycol in ('3', 'var3') then 'var3'
          end);

编辑：

如果您只为每个值包含多行数据：

select (case when mycol in ('1', 'var1') then 'var1'
             when mycol in ('2', 'var2') then 'var2'
             when mycol in ('3', 'var3') then 'var3'
        end),
       count(*) as Total
from mytable t
group by (case when mycol in ('1', 'var1') then 'var1'
               when mycol in ('2', 'var2') then 'var2'
               when mycol in ('3', 'var3') then 'var3'
          end);

总和列计数两个不同的值

1 个答案: