当我们需要知道mysql中的某个字段是否为空？怎么实现呢？

这里提供了5种方法进行查询：

isnull()

select * from users where email = 'xxxx' and isnull(deletedAt)

select * from users where email = 'xxxx' and deletedAt is null

is not nullis null

select * from users where email = 'xxxx' and deletedAt is not null

!isnull()

select * from users where email = 'xxxx' and !isnull(deletedAt)

select * from users where email = 'xxxx' and not isnull(deletedAt)

isfull

当查询条件为 null，用指定字符替代

select name,  isfull(gender,'未知') as gender  from users where email = 'xxxx'

以上就是mysql判断字段是否为空的详细内容!