mysql 里面的isnull()和ifnull() is null 和 is not null
usergrade表2.找到里面username是null的行SELECT * FROM usergrade WHERE ISNULL(USERNAME)SELECT * FROM usergrade WHERE USERNAME IS NULL3.找到里面username不是null的行SELECT * FROM usergrad
·
usergrade表
2.找到里面username是null的行
SELECT * FROM usergrade WHERE ISNULL(USERNAME)
SELECT * FROM usergrade WHERE USERNAME IS NULL
3.找到里面username不是null的行
SELECT * FROM usergrade WHERE USERNAME IS NOT NULL
4.列出所有的行,并且将username是null的字段替换为lxy
SELECT IFNULL(USERNAME,'lxy'),GRADE FROM usergrade
更多推荐
已为社区贡献2条内容
所有评论(0)