mysql - 如何在两个选择之间的mysql中使用算术减号？

Question

select player.ActionTime from question_log log inner join player_question player 
where log.ActionType='96'

select player.ActionTime from question_log log inner join player_question player 
where log.ActionType='97'

如何在 mysql 语法中做到这一点？选择ActionTime，其中ActionType为96减去另一个为97。算术减去。

Answer 1

SELECT t96.ActionTime - t97.ActionTime
FROM
(
    select player.ActionTime 
    from question_log log 
    inner join player_question player 
    where log.ActionType='96'
) t96
CROSS JOIN
(
    select player.ActionTime 
    from question_log log 
    inner join player_question player 
    where log.ActionType='97'
) t97

请注意，您的两个查询之间似乎没有任何关联，因此我只能建议使用CROSS JOIN(笛卡尔积)。如果您有不止一行 log.ActionType = '96' 或 log.ActionType = '97' 您将有很多结果行。