PostgreSQL Query使用相同的表值从同一个表中获取输出

Question

我有一张桌子

id  employee    leave_days  leave_type  type
1   ABC                 10       sick   remove
2   ABC                 20       sick   add
3   ABC                 15     Annual   remove
4   ABC                 50     Annual   add
5   XYZ                 10       sick   remove
6   XYZ                 20       sick   add
7   XYZ                 15     Annual   remove
8   XYZ                 50     Annual   add

从上表中我将按名称 leave_type 分组，然后我将合并行，输出应如下所示。

我必须按列名 leave_type 进行分组，然后添加名为 leave_allocated 的新列。在 leave_allocated 列中，只有值添加的类型列才会出现。

id  employee    leave_days  leave_type  leave_allocated
1   ABC             10          sick    20
2   ABC             15        Annual    50
3   XYZ             10          sick    20
4   XYZ             15        Annual    50

我尝试使用子查询我无法将内部查询与外部查询匹配。

Answer 1

这应该有帮助

SELECT id,
    employee,
    leave_dates,
    leave type,
    (SELECT leave_days
    FROM TABLE t2
    WHERE t2.id = t1.id
    AND t2.type = 'add'
    ) leave_allocated
FROM TABLE t1
WHERE t1.type = 'remove'