mysql查询最高最低 mysql字段空值在前端怎么检验 – 数据库 – 前端 mysql接入deny

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

is nullselect * from users where email = xxxx and deletedAt is null

is not nullselect * 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

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