如果任何字段包含NULL，则MySQL CONCAT返回NULL

一尘不染

如果任何字段包含NULL，则MySQL CONCAT返回NULL

mysql

我的“设备”表中有以下数据

affiliate_name  affiliate_location  model     ip             os_type    os_version

cs1             inter               Dell     10.125.103.25   Linux      Fedora  
cs2             inter               Dell     10.125.103.26   Linux      Fedora  
cs3             inter               Dell     10.125.103.27   NULL       NULL    
cs4             inter               Dell     10.125.103.28   NULL       NULL

我执行以下查询

SELECT CONCAT(`affiliate_name`,'-',`model`,'-',`ip`,'-',`os_type`,'-',`os_version`) AS device_name
FROM devices

返回下面给出的结果

cs1-Dell-10.125.103.25-Linux-Fedora
cs2-Dell-10.125.103.26-Linux-Fedora
(NULL)
(NULL)

如何得出这一点，以便它应该忽略NULL并且结果应该是

cs1-Dell-10.125.103.25-Linux-Fedora
cs2-Dell-10.125.103.26-Linux-Fedora
cs3-Dell-10.125.103.27-
cs4-Dell-10.125.103.28-

阅读 480

2020-05-17

共1个答案

一尘不染

NULL通过将其包装在空字符串中来转换值COALESCE

SELECT CONCAT(COALESCE(`affiliate_name`,''),'-',COALESCE(`model`,''),'-',COALESCE(`ip`,''),'-',COALESCE(`os_type`,''),'-',COALESCE(`os_version`,'')) AS device_name
FROM devices

2020-05-17