是否可以在核心数据中合并两个查询(来自同一实体)?在 SQL 中,如果实体被称为 t,则认为 T 具有以下数据:
+------+------+------+
| x | y | z |
+------+------+------+
| 1 | 11 | 2 |
| 1 | 12 | 3 |
| 2 | 11 | 1 |
| 3 | 12 | 3 |
然后我尝试运行以下查询(使用核心数据 - 不是 SQLite)
select x, y, sum(z)
from t
group by 1, 2
union
select x, 1 as y, sum(z)
from t
group by 1, 2
order by x, y, 1
;
+------+------+--------+
| x | y | sum(z) |
+------+------+--------+
| 1 | 1 | 5 |
| 1 | 11 | 2 |
| 1 | 12 | 3 |
| 2 | 1 | 1 |
| 2 | 11 | 1 |
| 3 | 1 | 3 |
| 3 | 12 | 3 |
+------+------+--------+
7 rows in set (0.00 sec)
可能吗?
谢谢!