php - 使用外键填充表

Question

我有一个这样的架构

CREATE TABLE TrainManager(
    train_name    VARCHAR(5) REFERENCES Train(name),
    station_id      INT REFERENCES Station(station_id)
);

这两个引用表具有间接关系。

control (ctrl_id, train_name);

controlremote (ctrl_id, station_id);

如您所知，为了获取火车名称和车站ID，我们需要进入其他两个表来比较ctrl_id除了比较 train_name 和 station_id 之外。

$query = "INSERT INTO `train` (train_name, station_id)
    SELECT t.train_name, st.station_id
    FROM train, station
    WHERE t.train_name = ( SELECT c.train_name FROM control c
                           WHERE c.train_name = t.train_name)
            AND
          st.station_id = ( SELECT cr.station_id FROM controlremote cr
                            WHERE cr.station_id = st.station_id)
            AND

但是我想不出一个合适的 SQL synatx 来比较 ctrl_id ...

Answer 1

INSERT INTO `train` (train_name, station_id)
SELECT control.train_name, controlremote.station_id
FROM control
LEFT JOIN controlremote ON control.ctrl_id = controlremote.ctrl_id

沿着这条路走下去。只需在 ctrl_id 上连接两个表即可。我希望我理解正确。