当前位置: 数据库>mysql
Mysql select语句设置默认值的方法
来源: 互联网 发布时间:2014-10-14
本文导语: 1.在没有设置默认值的情况下: 代码如下:SELECT userinfo.id, user_name, role, adm_regionid, region_name , create_timeFROM userinfoLEFT JOIN region ON userinfo.adm_regionid = region.id结果: 设置显示默认值: 代码如下:SELECT userinfo.id, user_name, role, adm_regionid,...
1.在没有设置默认值的情况下:
SELECT userinfo.id, user_name, role, adm_regionid, region_name , create_time
FROM userinfo
LEFT JOIN region ON userinfo.adm_regionid = region.id
结果:
SELECT userinfo.id, user_name, role, adm_regionid, IFNULL(region_name,0) as region_name, create_time
FROM userinfo
LEFT JOIN region ON userinfo.adm_regionid = region.id
即:如果region_name一列的值为空,则显示为0,结果为:
本文来自:http://blog.csdn.net/xyw_blog/article/details/26250331
代码如下:
SELECT userinfo.id, user_name, role, adm_regionid, region_name , create_time
FROM userinfo
LEFT JOIN region ON userinfo.adm_regionid = region.id
结果:
设置显示默认值:
代码如下:
SELECT userinfo.id, user_name, role, adm_regionid, IFNULL(region_name,0) as region_name, create_time
FROM userinfo
LEFT JOIN region ON userinfo.adm_regionid = region.id
即:如果region_name一列的值为空,则显示为0,结果为:
本文来自:http://blog.csdn.net/xyw_blog/article/details/26250331