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BigTows
Asked:2020-06-03 14:33:34 +0000 UTC2020-06-03 14:33:34 +0000 UTC

SQL查询输出当前机器位置

  • 772

有一张表（History_locations）

有必要显示机器的实际 id_location。那是

id_rollingcar | id_location

1 | 一

2 | 2个

3 | 一

我想是这样的：

SELECT DISTINCT id_rolling_car as id_car,
(SELECT HL.id_location FROM History_locations as HL 
 WHERE HL.id_rolling_car = id_car
 ORDER bY HL.date DESC LIMIT 1) as id_location
 FROM History_locations
mysql

1 个回答

  1. Best Answer

    你题里写的不好，因为你尝试select的时候，字段date也会塌陷，我觉得应该考虑到这一点，以免以后遇到同样的问题。

    作为一个选项：

    SELECT id_rolling_car, id_location, date
FROM history_locations
WHERE date IN (SELECT max(date) from history_locations GROUP BY id_rolling_car)
ORDER BY id_rolling_car
    • 1

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