MySQL查询，where后面怎么加判断，如果一个字段为null使用另外一个字段

Question

现在的查询语句

select * from bulldozer_overview
where
DATE_FORMAT(entry_time, "%Y-%m-%d") BETWEEN FROM_UNIXTIME(1523168970,'%Y-%m-%d') AND FROM_UNIXTIME(1623171661,'%Y-%m-%d')
                OR DATE_FORMAT(begin_time, "%Y-%m-%d") BETWEEN FROM_UNIXTIME(1523168970,'%Y-%m-%d') AND FROM_UNIXTIME(1623171661,'%Y-%m-%d')

在bulldozer_overview里面有两个字段begin_time、entry_time

如果begin_time为null则使用entry_time

请问这个where怎么改？

Answer 1

难道你想要的是这个？

select *
from bulldozer_overview
where DATE_FORMAT(IFNULL(entry_time,begin_time), "%Y-%m-%d") BETWEEN FROM_UNIXTIME(1523168970, '%Y-%m-%d') AND FROM_UNIXTIME
    (1625171661,
    '%Y-%m-%d');