我有一个postgres表，其中包含一些数据。每行都有一个与之关联的日期。我想提取月份为4月的行。这是我的postgres表数据的csv版本
,date,location,device,provider,cpu,mem,load,drops,id,latency,gw_latency,upload,download,sap_drops,sap_latency,alert_id
0,2018-02-10 11:52:59.342269+00:00,BEM,10.11.100.1,COD,6.0,23.0,11.75,0.0,,,,,,,,
1,2018-02-10 11:53:04.006971+00:00,VER,10.11.100.1,KOD,6.0,23.0,4.58,0.0,,,,,,,,
2,2018-03-25 20:28:36.186015+00:00,RET,10.11.100.1,POL,7.0,26.0,9.83,0.0,,86.328,5.0,4.33,15.33,0.0,23.0,
3,2018-03-25 20:28:59.155453+00:00,ASR,10.12.100.1,VOL,5.0,14.0,2.67,0.0,,52.406,12.0,2.17,3.17,0.0,28.0,
4,2018-04-01 13:16:44.472119+00:00,RED,10.19.0.1,SEW,6.0,14.0,2.77,0.0,,52.766,2.0,3.25,2.29,0.0,1.0,0.0
5,2018-04-01 13:16:48.478708+00:00,RED,10.19.0.1,POL,6.0,14.0,4.065,0.0,,52.766,1.0,6.63,1.5,0.0,1.0,0.0
6,2018-04-06 21:00:44.769702+00:00,GOK,10.61.100.1,FDE,4.0,22.0,3.08,0.0,,54.406,8.0,3.33,2.83,0.0,19.0,0.0
7,2018-04-06 21:01:07.211395+00:00,WER,10.4.100.1,FDE,3.0,3.0,9.28,0.0,,0.346,2.0,10.54,8.02,0.0,33.0,0.0
8,2018-04-13 11:18:08.411550+00:00,DER,10.19.0.1,CVE,14.0,14.0,7.88,0.0,,50.545,2.0,6.17,9.59,0.0,1.0,0.0
9,2018-04-13 11:18:12.420974+00:00,RTR,10.19.0.1,BOL,14.0,14.0,1.345,0.0,,50.545,1.0,2.26,0.43,0.0,1.0,0.0
所以我只想要有一个月的四月数据的行，这样我就会有一个看起来像这样的表
4,2018-04-01 13:16:44.472119+00:00,RED,10.19.0.1,SEW,6.0,14.0,2.77,0.0,,52.766,2.0,3.25,2.29,0.0,1.0,0.0
5,2018-04-01 13:16:48.478708+00:00,RED,10.19.0.1,POL,6.0,14.0,4.065,0.0,,52.766,1.0,6.63,1.5,0.0,1.0,0.0
6,2018-04-06 21:00:44.769702+00:00,GOK,10.61.100.1,FDE,4.0,22.0,3.08,0.0,,54.406,8.0,3.33,2.83,0.0,19.0,0.0
7,2018-04-06 21:01:07.211395+00:00,WER,10.4.100.1,FDE,3.0,3.0,9.28,0.0,,0.346,2.0,10.54,8.02,0.0,33.0,0.0
8,2018-04-13 11:18:08.411550+00:00,DER,10.19.0.1,CVE,14.0,14.0,7.88,0.0,,50.545,2.0,6.17,9.59,0.0,1.0,0.0
9,2018-04-13 11:18:12.420974+00:00,RTR,10.19.0.1,BOL,14.0,14.0,1.345,0.0,,50.545,1.0,2.26,0.43,0.0,1.0,0.0
现在如果我尝试使用以下查询提取特定日期
select * from metrics_data where date = 2018-04-13;
我收到错误消息
No operator matches the given name and argument type(s). You might need to add explicit type casts.
如何获取4月份的行并将其存储在新表中april_data？
以下是我现有表格的结构
Column | Type | Modifiers | Storage | Stats target | Description
-------------+--------------------------+-----------+----------+--------------+-------------
date | timestamp with time zone | | plain | |
location | character varying(255) | | extended | |
device | character varying(255) | | extended | |
provider | character varying(255) | | extended | |
cpu | double precision | | plain | |
mem | double precision | | plain | |
load | double precision | | plain | |
drops | double precision | | plain | |
id | integer | | plain | |
latency | double precision | | plain | |
gw_latency | double precision | | plain | |
upload | double precision | | plain | |
download | double precision | | plain | |
sap_drops | double precision | | plain | |
sap_latency | double precision | | plain | |
alert_id | double precision | | plain | |
答案 0 :(得分：3)
表格中date列的类型为timestamp with time zone，其格式为YYYY:MM:DD HH24:MI:SS.MS。在查询中，您进行了操作timestamp with time zone = date，因此会引发错误。
所以，如果你想修复它，你应该将一方修复为另一方的类型。
在你的情况下，我建议如下：
完全匹配1天。
select * from metrics_data where date(date) = '2018-04-13';
1个月内匹配。
select * from metrics_data where date BETWEEN '2018-04-01 00:00:00' AND '2018-04-30 23:59:59.999';
OR
select * from metrics_data where date(date) BETWEEN '2018-04-01' AND '2018-04-30';
OR
select * from metrics_data where to_char(date,'YYYY-MM') = '2018-04';
仅匹配April。
select * from metrics_data where to_char(date,'MM') = '04';
OR
select * from metrics_data where extract(month from date) = 4;
希望这个答案可以帮到你。
答案 1 :(得分：1)
字符串文字周围需要单引号
PostgreSQL会自动将其转换为正确的数据类型（timestamp with time zone）。
您可以使用extract功能仅选择4月份的日期：
SELECT * FROM yourtable WHERE extract (month FROM yourtable.date) = 4;