如何在postgreSQL中的一行中獲取多個值？

Question

我在postgreSQL9.4中有數據庫表名emp_leave

|emp_name|leave_type|total_lday|
| Tame   |    PL    |     3    |
| Tame   |    UL    |     4    |

我想要查詢結果

|emp_name|paid_leave|unpaid_leave|
| Tame   |    3     |      4     |    

Answer 1

Postgresql 9.4還有FILTER子句來進行條件聚合：

select emp_name, 
       max(total_lday) FILTER (where leave_type = 'PL') as paid_leave,
       max(total_lday) FILTER (where leave_type = 'UL') as unpaid_leave
from emp_leave
group by emp_name

（ANSI SQL-2016，功能T612，“高級OLAP操作”。）

Answer 2

你可以嘗試下面 - 使用條件聚合

select emp_name, 
  max(case when leave_type='PL' then total_lday end) as paid_leave,
  max(case when leave_type='UL' then total_lday end) as unpaid_leave
from emp_leave
group by emp_name