Question

我当前的表格如下：

+-------+------+
| Level | Team |
+-------+------+
|     1 |    1 |
|     2 |    1 |
|     2 |    1 |
|     3 |    2 |
|     3 |    2 |
|     3 |    2 |
+-------+------+

我想按级别分组，并且知道两个团队的级别数。通过使用以下命令，我可以轻松获得单个团队的人数：

SELECT Level, Count(Team)
FROM table
WHERE Team = 1
GROUP BY Level
SORT BY Level;
+-------+-------------+
| Level | Team1_Count |
+-------+-------------+
|     1 |           1 |
|     2 |           2 |
|     3 |           0 |
+-------+-------------+

但是，我想要的最终结果如下：

+-------+-------------+-------------+
| Level | Team1_Count | Team2_Count |
+-------+-------------+-------------+
|     1 |           1 |           0 |
|     2 |           2 |           0 |
|     3 |           0 |           3 |
+-------+-------------+-------------+

删除WHERE子句可得出每个级别的总数，但不会将其分成团队。如何创建两个新列并显示每个级别的计数？

Answer 1

使用combineLatest(...this.filtersList.map((f) => f.filtersChanges).filter(f => f !== null)).subscribe( ... );和case表达式尝试以下操作。这是demo。

sum

输出

select
  level,
  sum(case when team = 1 then 1 else 0 end) as Team1_count,
  sum(case when team = 2 then 1 else 0 end) as Team2_count
from table
group by
  level
order by
  level

如果您使用的是postgreSQL，则可以将| level | Team1_count | Team2_count | | ----- | ----------- | ----------- | | 1 | 1 | 0 | | 2 | 2 | 0 | | 3 | 0 | 3 |与filter一起使用，如下所示

count

从行值创建新列，然后分组依据

1 个答案: