如何使用带CASE语句的CONCAT删除查询中的空值

时间：2016-09-23 06:01:28

标签： mysql database

我想忽略查询中的空值。

我尝试在concat中使用case语句，但是它给了我null值 表结构

CREATE TABLE `UserInfo` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `user_id` int(11) NOT NULL,
  `key` varchar(200) NOT NULL,
  `value` longtext NOT NULL,
  `created_on` varchar(200) NOT NULL,
  `updated_on` varchar(200) NOT NULL,
  `status` int(11) NOT NULL,
  PRIMARY KEY (`id`)
) ENGINE=MyISAM AUTO_INCREMENT=111 DEFAULT CHARSET=latin1;  

insert  into `UserInfo`(`id`,`user_id`,`key`,`value`,`created_on`,`updated_on`,`status`) 
values (69,11132,'country','India','','',1),(67,11132,'city','Gurgaon','','',1),(68,11132,'state','Haryana','','',1),(66,11132,'address','CyberHub','','',1),(64,11131,'state','Delhi','','',1),(65,11131,'country','India','','',1),(63,11131,'city','','','',1),(62,11131,'address','Lajpat Nagar','','',1),(60,11130,'state','Haryana','','',1),(61,11130,'country','India','','',1),(58,11130,'address','','','',1),(59,11130,'city','Gurgaon','','',1),(787,11130,'password','0192023a7bbd73250516f069df18b500','30-03-2016 06:58:18','30-03-2016 06:58:18',1),(788,11131,'password','04d237e63ebc1acbb3fcacf3e1a846cb','30-03-2016 06:58:18','26-04-2016 07:46:33',1),(789,11132,'password','0192023a7bbd73250516f069df18b500','30-03-2016 06:58:18','24-05-2016 11:47:35',1),(1123,11130,'parent','0','','',1),(1124,11131,'parent','0','','',1),(1125,11132,'parent','0','','',1),(2036,11136,'gcm_id','fLJ8vwS5yWc','04-05-2016 06:01:07','04-05-2016 06:01:07',1),(2035,11136,'push_id','fLJ8vwS5yWc:APA91bFO-hLW5uQqDQTABkilyOd9MzuMRhQMI8uNLRGh4fjaq3Bk1OvFmb7QFVKYpqqJZFPQ78Y1h0349IZuxq0EcxZ8VCHJOTOhhsqi1VxQ2A7TVLY-phDcN6sj80x8R7KoOocQKPLl','04-05-2016 06:01:07','04-05-2016 06:01:07',1),(2993,11570,'transaction_limit','100','16-09-2016 10:34:13','16-09-2016 10:34:13',1),(2992,11570,'otp','461178','16-09-2016 10:32:48','16-09-2016 10:32:48',1),(2991,11570,'password','1e28284f59e926547bb6793ad8723722','16-09-2016 10:32:48','16-09-2016 10:32:48',1),(2990,11570,'imei','353918057482479','16-09-2016 10:32:48','16-09-2016 10:32:48',1),(2989,11570,'push_id','dGxCE33MJgg:APA91bFCzSkvIDEcZcgmmSxVocFNZfLI8owLsdElmF-Et0wUH0mxUbQ9mIZDMjlhqClTOYiSxhSaVBdESwJW6J58hsyEF0LUMgXRTGdnEwWdbHJmm3EZuHDHzniMaJGcCKvALrcxtQt8','16-09-2016 10:32:48','16-09-2016 10:32:48',1),(2987,11570,'gender','Male','16-09-2016 10:32:48','16-09-2016 10:32:48',1),(2026,11136,'gcm_id','fLJ8vwS5yWc','03-05-2016 06:28:52','03-05-2016 06:28:52',1),(2025,11136,'push_id','fLJ8vwS5yWc:APA91bFO-hLW5uQqDQTABkilyOd9MzuMRhQMI8uNLRGh4fjaq3Bk1OvFmb7QFVKYpqqJZFPQ78Y1h0349IZuxq0EcxZ8VCHJOTOhhsqi1VxQ2A7TVLY-phDcN6sj80x8R7KoOocQKPLl','03-05-2016 06:28:52','03-05-2016 06:28:52',1),(2024,11136,'gcm_id','cU6PMImJ9Ms','02-05-2016 17:02:39','02-05-2016 17:02:39',1),(2023,11136,'push_id','cU6PMImJ9Ms:APA91bHA-a_joHtzEBgoAPRxRCXObeJLlCCNSxlCM-jBZKvSUEFvhLZEyqPbbsIDyWc2emZa1yBerOQLGXgzzNKZmcJYCgcF8KBdm9McVBiDKzU_OthjGnROZyTC5EvnI7Z4QivXnokA','02-05-2016 17:02:39','02-05-2016 17:02:39',1),(2022,11136,'gcm_id','cU6PMImJ9Ms','02-05-2016 16:38:55','02-05-2016 16:38:55',1),(2020,11136,'gcm_id','c2sOUeSpIuQ','02-05-2016 16:37:53','02-05-2016 16:37:53',1),(2021,11136,'push_id','cU6PMImJ9Ms:APA91bHA-a_joHtzEBgoAPRxRCXObeJLlCCNSxlCM-jBZKvSUEFvhLZEyqPbbsIDyWc2emZa1yBerOQLGXgzzNKZmcJYCgcF8KBdm9McVBiDKzU_OthjGnROZyTC5EvnI7Z4QivXnokA','02-05-2016 16:38:55','02-05-2016 16:38:55',1),(2019,11136,'push_id','c2sOUeSpIuQ:APA91bGskmvA5VVmxozMHKX3qHc16bdmk9h5gFTEPP8uFUYsO-doGCnkTE-ZtpMGeuuk2YCt3Ja56ey7nIga6aO7wpof2fI5zcgYdFACKvkcddNAlY4UhIO39tfyG3m4DZkmaLqw2Kxu','02-05-2016 16:37:53','02-05-2016 16:37:53',1),(2018,11136,'gcm_id','djRRW-PrS2Q','02-05-2016 16:30:02','02-05-2016 16:30:02',1),(2016,11136,'gcm_id','c2sOUeSpIuQ','02-05-2016 16:25:00','02-05-2016 16:25:00',1),(2017,11136,'push_id','djRRW-PrS2Q:APA91bFbB5SO0wY2TlGCZBmgbZUr0c1FXH5FE22YxOCf4tA7uM1V45T2cTY1aitIQKrf1bjrPB-zZUCDPNdL8-2SYnEawrFTdVjL5w1VuVI2kA89ixlK6jlpmNOoJ7wQnWqQoCFkcd9_','02-05-2016 16:30:02','02-05-2016 16:30:02',1),(2015,11136,'push_id','c2sOUeSpIuQ:APA91bGskmvA5VVmxozMHKX3qHc16bdmk9h5gFTEPP8uFUYsO-doGCnkTE-ZtpMGeuuk2YCt3Ja56ey7nIga6aO7wpof2fI5zcgYdFACKvkcddNAlY4UhIO39tfyG3m4DZkmaLqw2Kxu','02-05-2016 16:25:00','02-05-2016 16:25:00',1),(2014,11136,'gcm_id','djRRW-PrS2Q','01-05-2016 07:38:26','01-05-2016 07:38:26',1),(2013,11136,'push_id','djRRW-PrS2Q:APA91bFbB5SO0wY2TlGCZBmgbZUr0c1FXH5FE22YxOCf4tA7uM1V45T2cTY1aitIQKrf1bjrPB-zZUCDPNdL8-2SYnEawrFTdVjL5w1VuVI2kA89ixlK6jlpmNOoJ7wQnWqQoCFkcd9_','01-05-2016 07:38:26','01-05-2016 07:38:26',1),(2012,11136,'gcm_id','c2sOUeSpIuQ','01-05-2016 07:29:00','01-05-2016 07:29:00',1),(2011,11136,'push_id','c2sOUeSpIuQ:APA91bGskmvA5VVmxozMHKX3qHc16bdmk9h5gFTEPP8uFUYsO-doGCnkTE-ZtpMGeuuk2YCt3Ja56ey7nIga6aO7wpof2fI5zcgYdFACKvkcddNAlY4UhIO39tfyG3m4DZkmaLqw2Kxu','01-05-2016 07:29:00','01-05-2016 07:29:00',1),(2010,11439,'otp','467957','01-05-2016 07:04:42','16-08-2016 10:48:09',0),(2009,11438,'otp','631866','30-04-2016 09:36:54','06-05-2016 13:32:15',0),(2008,11438,'otp','586481','30-04-2016 09:22:55','06-05-2016 13:32:15',0),(2007,11438,'otp','971411','30-04-2016 09:19:52','06-05-2016 13:32:15',0),(2006,11136,'gcm_id','eNJISa-1OGA','30-04-2016 09:05:22','30-04-2016 09:05:22',1),(2005,11136,'push_id','eNJISa-1OGA:APA91bGB6m0d-RzoFUvw1SRsCIOEvfO3BjLUiMsZRdHnHlEGq6QKV9sVqCdLai25_dxTvUeuQVzFU5scKCaPvlDaG_VZ-V51t1AG4EEAtJdjGNQwhITF2eh0E24D_J9vPCQ3nIzanq8f','30-04-2016 09:05:22','30-04-2016 09:05:22',1),(2004,11445,'transaction_limit','2000','30-04-2016 09:03:41','30-04-2016 09:03:41',1),(2003,11445,'otp','230253','30-04-2016 09:02:35','30-04-2016 09:02:35',1),(2002,11445,'password','25d55ad283aa400af464c76d713c07ad','30-04-2016 09:02:35','30-04-2016 09:02:35',1),(2001,11445,'push_id','ccPZg_PD7bo:APA91bFrUK8JPZfI6tSBKDgETeeI_aE6RA-FTFh6pS4fluVv6jHIVKUyDAEurIJWo49nWa52q6Zas7F2DI_KNkDX-HVq_TXuO36dRN9JditQVGR9HUq8avS5QEzYA2gwYjyo7Bosrsyz','30-04-2016 09:02:35','30-04-2016 09:02:35',1),(2000,11445,'gcm_id','ccPZg_PD7bo','30-04-2016 09:02:35','30-04-2016 09:02:35',1),(1999,11445,'gender','Male','30-04-2016 09:02:35','30-04-2016 09:02:35',1),(1998,11445,'bank_name','DCB Bank','30-04-2016 09:02:35','30-04-2016 09:02:35',1),(1997,11136,'gcm_id','cXK3F2L7Fcw','30-04-2016 08:37:01','30-04-2016 08:37:01',1)

我尝试了查询，但它也产生了空列值 我想忽略空值

 SELECT
  CONCAT(
    CASE WHEN ui.key='gender' THEN ui.value ELSE '' END,
    CASE WHEN ui.key='password' THEN ui.value ELSE '' END,
    CASE WHEN ui.key='transaction_limit' THEN ui.value ELSE '' END
  ) AS test,
  ui.id,ui.user_id,ui.key,ui.value
FROM UserInfo ui 
WHERE ui.user_id=11445

Result :
------------------------------------------------------------------------------------------------------------------
test    id   user_id    key                 value
2000    2004  11445    transaction_limit    2000
        2003  11445    otp                  230253
25d55ad 2002  11445    password             25d55ad..
        2001  11445    push_id              ccPZg_P..
        2000  11445    gcm_id               ccPZg_PD7bo
Male    1999  11445    gender               Male
        1998  11445 bank_name               DCB Bank

------------------------------------------------------------------------------------------------------------------

Desire Result :
------------------------------------------------------------------------------------------------------------------
test    id   user_id    key                 value
2000    2004  11445    transaction_limit    2000
25d55ad 2002  11445    password             25d55ad..
Male    1999  11445    gender               Male

------------------------------------------------------------------------------------------------------------------

2 个答案:

答案 0 :(得分：0)

您可以使用 CONCAT_WS 代替 CONCAT 。 CONCAT_WS 的第一个arg是separetor

<强>样品 

mysql> select CONCAT('a','b',NULL,'d','e');
+------------------------------+
| CONCAT('a','b',NULL,'d','e') |
+------------------------------+
| NULL                         |
+------------------------------+
1 row in set (0,01 sec)

mysql> select CONCAT_WS(',','a','b',NULL,'d','e');
+-------------------------------------+
| CONCAT_WS(',','a','b',NULL,'d','e') |
+-------------------------------------+
| a,b,d,e                             |
+-------------------------------------+
1 row in set (0,00 sec)

mysql>

<强>手册

  

CONCAT_WS（）代表Concatenate With Separator，是一个特殊的   形式的CONCAT（）。第一个参数是其余部分的分隔符   争论。在字符串之间添加分隔符   级联。分隔符可以是字符串，其余部分也可以   参数。

     

如果分隔符为NULL，则结果为NULL;所有其他NULL值   被跳过了。这使得CONCAT_WS（）适合您的需要   连接一些值，避免丢失所有信息   它们是NULL。

答案 1 :(得分：0)

对于wron回答抱歉：

你可以添加：

SELECT
  CONCAT(
    CASE WHEN ui.key='gender' THEN ui.value ELSE '' END,
    CASE WHEN ui.key='password' THEN ui.value ELSE '' END,
    CASE WHEN ui.key='transaction_limit' THEN ui.value ELSE '' END
  ) AS test,
  ui.id,ui.user_id,ui.key,ui.value
FROM UserInfo ui 
WHERE ui.user_id=11445
HAVING test <> '';

<强>样品 

mysql> SELECT
    ->   CONCAT(
    ->     CASE WHEN ui.key='gender' THEN ui.value ELSE '' END,
    ->     CASE WHEN ui.key='password' THEN ui.value ELSE '' END,
    ->     CASE WHEN ui.key='transaction_limit' THEN ui.value ELSE '' END
    ->   ) AS test,
    ->   ui.id,ui.user_id,ui.key,ui.value
    -> FROM UserInfo ui
    -> WHERE ui.user_id=11445
    -> HAVING test <> '';
+----------------------------------+------+---------+-------------------+----------------------------------+
| test                             | id   | user_id | key               | value                            |
+----------------------------------+------+---------+-------------------+----------------------------------+
| 2000                             | 2004 |   11445 | transaction_limit | 2000                             |
| 25d55ad283aa400af464c76d713c07ad | 2002 |   11445 | password          | 25d55ad283aa400af464c76d713c07ad |
| Male                             | 1999 |   11445 | gender            | Male                             |
+----------------------------------+------+---------+-------------------+----------------------------------+
3 rows in set (0,00 sec)

mysql>
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