計算SQL Server中的每個不同值

Question

我有一個像這樣的表tbl_demo ：

              aliasname is_correct
                    10  INCORRECT
                    10  INCORRECT
                    10  INCORRECT
                    10  CORRECT
                    10  CORRECT
                    10  NOT SOLVED
                    9   INCORRECT
                    9   INCORRECT
                    9   CORRECT

我創建了一個查詢：

select 
    aliasname, 
    count(*) as quest_count,  
    is_correct 
from 
    tbl_demo 
group by 
    aliasname, is_correct order by aliasname

我得到這樣的輸出

              aliasname quest_count  is_correct
              ---------------------------------
              10          2            CORRECT
              10          3            INCORRECT
              10          1            NOT SOLVED
               9          1            CORRECT
               9          2            INCORRECT

但我希望在9中0，而不是解決

就像這樣的一行

                9         0            NOT SOLVED

這可以輕松實現，以及如何實現？

Answer 1

您可以通過使用cross join生成所有可能的組合，並使用left join來引入原始數據。 其余的只是聚合：

select a.aliasname, count(d.aliasname) as quest_count, ic.is_correct
from (select distinct aliasname from tbl_demo
     ) a cross join
     (select distinct is_correct from tbl_demo
     ) ic left outer join
     tbl_demo d
     on d.aliasname = a.aliasname and d.is_correct = ic.is_correct
group by a.aliasname, ic.is_correct;