sql - 表“ session ”中有一个名为“ap”的列，但无法在查询的此部分中引用

我有一个“会议”桌：

--------------------+-----------------------------+------------------------------------------------------+-----------+---------------------+----------
 id                 | integer                     | NOT NULL DEFAULT nextval('session_id_seq'::regclass) | plain     |                     |
 ssid               | integer                     |                                                      | plain     |                     |
 ap                 | integer                     |                                                      | plain     |                     |
 associationtime    | timestamp without time zone |                                                      | plain     |                     |
 disassociationtime | timestamp without time zone |                                                      | plain     |                     |
 sessionduration    | character varying(100)      |                                                      | extended  |                     |
 clientip           | character varying(100)      |                                                      | extended  |                     |
 clientmac          | character varying(100)      |                                                      | extended  |                     |
 devicename         | character varying(100)      |                                                      | extended  |                     |
 tx                 | character varying(100)      |                                                      | extended  |                     |
 rx                 | character varying(100)      |                                                      | extended  |                     |
 protocol           | character varying(100)      |                                                      | extended  |                     |
 snr                | character varying(100)      |                                                      | extended  |                     |
 rssi               | character varying(100)      |                                                      | extended  |                     |
 dataretries        | character varying(100)      |                                                      | extended  |                     |
 rtsretries         | character varying(100)      |                                                      | extended  |                     |

我想添加新记录，但前提是它不存在。我就是这样用NOT IN：

INSERT INTO session (ssid, ap, associationtime, disassociationtime, sessionduration, clientip, clientmac, devicename, tx, rx, protocol, snr, rssi, dataretries, rtsretries)
SELECT 26, 951, 'Mon Jun 16 17:39:35 MSK 2014', 'Mon Jun 16 17:44:35 MSK 2014', '5 min 0 sec', '172.24.6.198', '00:3a:9a:86:7d:20', 'KZN-5508', '0', '0', '802.11g', '10', '-76', '191', '0'
WHERE (26, 951, 'Mon Jun 16 17:39:35 MSK 2014', 'Mon Jun 16 17:44:35 MSK 2014', '5 min 0 sec', '172.24.6.198', '00:3a:9a:86:7d:20', 'KZN-5508', '0', '0', '802.11g', '10', '-76', '191', '0')
NOT IN (
        SELECT ssid, ap, associationtime, disassociationtime, sessionduration, clientip, clientmac, devicename, tx, rx, protocol, snr, rssi, dataretries, rtsretries
        FROM session)

但它的工作非常缓慢。现在我想测试一下：

INSERT INTO SESSION (ssid, ap, associationtime, disassociationtime, sessionduration, clientip, clientmac, devicename, tx, rx, protocol, snr, rssi, dataretries, rtsretries)
SELECT 24, 968, 'Mon Jun 16 17:39:35 MSK 2014', 'Mon Jun 16 17:44:35 MSK 2014', '5 min 0 sec', '10.96.44.22', '00:3a:9a:86:6b:30', 'KZN-5508', '0', '0', '802.11g', '0', '-128', '0', '0'
WHERE
    NOT EXISTS (
        SELECT (ssid, ap, associationtime, disassociationtime, sessionduration, clientip, clientmac, devicename, tx, rx, protocol, snr, rssi, dataretries, rtsretries)
        FROM SSID
        WHERE ssid=24 AND ap=968
        AND associationtime='Mon Jun 16 17:39:35 MSK 2014'
        AND disassociationtime='Mon Jun 16 17:44:35 MSK 2014'
        AND sessionduration='5 min 0 sec' AND clientip='10.96.44.22'
        AND clientmac='00:3a:9a:86:6b:30' AND devicename='KZN-5508'
        AND tx='0' AND rx='0'AND protocol='802.11g' AND snr='0'
        AND rssi='-128' AND dataretries='0' AND rtsretries='0');

但console说：

There is a column named "ap" in table "session", but it cannot be referenced from this part of the query.

怎么了？

最佳答案

是否SSID是表的名称？

INSERT INTO SESSION (ssid, ap,  ...)
SELECT 24, 968, ...
WHERE  NOT EXISTS (
   SELECT 1         -- irrelevant what you put here
   FROM  session   -- assuming you want this instead of SSID
   WHERE  ssid=24
   AND    ap=968
   AND    ...
  )