如何在 postgreSQL 的一行中获取多个值？

Question

我有数据库 table name emp_leave in postgreSQL9.4 like

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

我想要这样的查询结果

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

Answer 1

您可以尝试以下 - 使用条件聚合

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

Answer 2

Postgresql 9.4 也有 FILTER 子句来进行条件聚合：

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，特性 T612，“高级 OLAP 操作”。)

如何在 postgreSQL 的一行中获取多个值？

How to get multiple value in one row in postgreSQL?

sql

postgresql-9.4