我有一个表MSGCOUNT，如下所示：
SERVER CHANNEL VALUE VARIABLE VARNAME DATES TIME
---------------------------------------------------------------------
1 A 133 MessageCount MSG_COUNT_A 12-NOV-18 10:16:56
1 A 129 MessageCount MSG_COUNT_A 12-NOV-18 10:13:26
1 A 120 MessageCount MSG_COUNT_A 12-NOV-18 10:00:55
2 B 210 MessageCount MSG_COUNT_B 12-NOV-18 21:42:45
2 B 200 MessageCount MSG_COUNT_B 12-NOV-18 21:41:25
2 B 195 MessageCount MSG_COUNT_B 12-NOV-18 21:41:19
我希望能够统计当天收到的总邮件数。
查询结果如下：
SERVER CHANNEL VALUE VARIABLE VARNAME DATE
----------------------------------------------------------
1 A 13 MessageCount MSG_COUNT_A 12-NOV-18
2 B 15 MessageCount MSG_COUNT_B 12-NOV-18
我尝试使用各种功能，无论是解析功能还是其他功能，但以下是最新尝试：
select server, channel, value, variable, varname, date
from
(
select time_interval as start_interval,
time_interval as end_interval,
round(MSG, 2) total_msg_recv,
channel,
server
from
(
select substr(DATES, 1,9),
round(VALUE,2) MSG,
channel,
server
from MSGCOUNT
)
)
group by date, server, channel
order by date
这将产生以下结果（这是错误的）：
SERVER CHANNEL VALUE VARIABLE VARNAME DATE
-----------------------------------------------------
1 A 133 MessageCount MSG_COUNT_A 12-NOV-18
2 B 210 MessageCount MSG_COUNT_B 12-NOV-18
谢谢
答案 0 :(得分：1)
做一个简单的减法会做吗？
SQL> with msgcount(server, channel, value, dates) as
2 (select 1, 'a', 133, date '2018-11-12' from dual union all
3 select 1, 'a', 129, date '2018-11-12' from dual union all
4 select 1, 'a', 120, date '2018-11-12' from dual union all
5 --
6 select 2, 'b', 210, date '2018-11-12' from dual union all
7 select 2, 'b', 200, date '2018-11-12' from dual union all
8 select 2, 'b', 195, date '2018-11-12' from dual
9 )
10 select server, channel, max(value) - min(value) diff, dates
11 from msgcount
12 group by server, channel, dates
13 order by server;
SERVER C DIFF DATES
---------- - ---------- ----------
1 a 13 12.11.2018
2 b 15 12.11.2018
SQL>
尚不清楚DATES和TIME是什么（哪种数据类型）；我认为，它应该是DATE数据类型的单个列。如果是这样，您应该TRUNC对其进行设置（例如TRUNC(DATES)）并删除时间部分，因为在这里这并不重要。
如果您提供更多信息，则该查询可能会更改，但总体思路还是可以的。