根据列值排列数据

Question

我有一张具有以下结构的桌子。

+ ----------------------+--------------+--------+
| timeStamp             | value        | type   |
+ ----------------------+--------------+--------+
| '2010-01-14 00:00:00' | '11787.3743' | 'mean' |
| '2018-04-03 14:19:21' | '9.9908'     | 'std'  |
| '2018-04-03 14:19:21' | '11787.3743' | 'min'  |
+ ----------------------+--------------+--------+

现在我想写一个select查询，我可以根据类型获取数据。

+ ----------------------+--------------+-------------+----------+
| timeStamp             | mean_type    | min_type    | std_type |
+ ----------------------+--------------+-------------+----------+
| '2010-01-14 00:00:00' | '11787.3743' |             |          |
| '2018-04-03 14:19:21' |              |             | '9.9908' |
| '2018-04-03 14:19:21' |              | '11787.3743 |          |
+ ----------------------+--------------+-------------+----------+

请帮助我如何通过编写查询在postgres数据库中执行此操作。我还想以10分钟的间隔获取数据。

Answer 1

使用with my_table(timestamp, value, type) as ( values ('2010-01-14 00:00:00', 11787.3743, 'mean'), ('2018-04-03 14:19:21', 9.9908, 'std'), ('2018-04-03 14:19:21', 11787.3743, 'min') ) select timestamp, case type when 'mean' then value end as mean_type, case type when 'min' then value end as min_type, case type when 'std' then value end as std_type from my_table; timestamp | mean_type | min_type | std_type ---------------------+------------+------------+---------- 2010-01-14 00:00:00 | 11787.3743 | | 2018-04-03 14:19:21 | | | 9.9908 2018-04-03 14:19:21 | | 11787.3743 | (3 rows) ：

declare
    v_ids int[];   
begin
    select array_agg(id) INTO v_ids
      from mytable1
     where host = p_host;

    --use v_ids...

end;