Question

我有一个数据库，其中包含表Plane，表Flight，这基本上是飞机执行的Flight，然后对于每个航班，我都解决了M：N表，该表仅包含Flight和Destination的外键，表中有2个条目Destination，要了解Departure和Arrival之间的差异，表Destination与表Type（Departure and Arrival，在另一个表中设置，该行有2行，“ Zacetna” = Departure，“ Koncna” = Arrival）相关联。表目标还具有到表日期的连接，该表包含日期时间。

我想减去每个航班的到达和离开时间，然后求和飞机是否有多个航班。

我试图先将它们全部相减然后再相减，但是那没有用，然后我试图进行分组依据，但是没有运气。

在所附图片中。名为“ Falcon FX 3000”的飞机有2个航班，分别是idFlight 5和6。要获得预期的结果，我将不得不这样做

( Destination_6_Date - Destination_5_Date) + (Destination_4_Date - Destination_7_Date) 但我的解决方案都无效

SELECT d.Ime, letD.Destinacija_idDestinacija, l.idLet,tip.Tip,  t.Termin
FROM Letalo p
INNER JOIN Let l ON l.Letalo_idLetalo = p.idLetalo
INNER JOIN Let_Has_Destinacija letD on letD.Let_idLet = l.idLet
INNER JOIN Destinacija d on d.idDestinacija = letD.Destinacija_idDestinacija
INNER JOIN Termin t on t.idTermin = d.Termin_idTermin
INNER JOIN Tip_Destinacije tip on tip.idTip_Destinacije = Tip_Destinacije_idTip_Destinacije WHERE p.Naziv='Falcon FX 3000';

https://i.imgur.com/5r2G9yI.png

https://i.imgur.com/3CIfbUN.png

Sorry for the ERDiagram for being in the different language
Letalo = Plane
Let = Flight
Let_Has_Destinacija = Solved M:N, holding Flight ID and Destination ID
Destinacija = Destination
Termin = Date
Tip_Destinacija = Type

编辑这是成功的GROUP BY查询，它返回有效的计算，现在我只需要对它们进行求和。我猜想这将通过子查询完成，但是我不太了解，因为我是MySQL的新手

SELECT d.Ime as Name, letD.Destinacija_idDestinacija as Destination, l.idLet as idFlight,tip.Tip as Type,  CAST(t.Termin as DATE), timediff(Max(t.Termin), min(t.Termin))
FROM Letalo p
INNER JOIN Let l ON l.Letalo_idLetalo = p.idLetalo
INNER JOIN Let_Has_Destinacija letD on letD.Let_idLet = l.idLet
INNER JOIN Destinacija d on d.idDestinacija = letD.Destinacija_idDestinacija
INNER JOIN Termin t on t.idTermin = d.Termin_idTermin
INNER JOIN Tip_Destinacije tip on tip.idTip_Destinacije = Tip_Destinacije_idTip_Destinacije WHERE p.Naziv='Falcon FX 3000'
GROUP BY l.idLet;

https://i.imgur.com/hUXZDnQ.png

编辑2 通过使用临时表，我设法求出了飞行时间，但是我必须对此使用两个查询，这不是我想要的。

DROP TABLE IF EXISTS tempTime;
CREATE TEMPORARY TABLE tempTime (
SELECT timediff(Max(t.Termin), min(t.Termin)) as FlightTime
    FROM Letalo p
    INNER JOIN Let l ON l.Letalo_idLetalo = p.idLetalo
    INNER JOIN Let_Has_Destinacija letD on letD.Let_idLet = l.idLet
    INNER JOIN Destinacija d on d.idDestinacija = letD.Destinacija_idDestinacija
    INNER JOIN Termin t on t.idTermin = d.Termin_idTermin
    INNER JOIN Tip_Destinacije tip on tip.idTip_Destinacije = Tip_Destinacije_idTip_Destinacije WHERE p.Naziv='Falcon FX 3000'
GROUP BY l.idLet);

SELECT SEC_TO_TIME(SUM(TIME_TO_SEC(FlightTime))) as FlownTime FROM tempTime;
DROP TABLE IF EXISTS tempTime;

https://i.imgur.com/HlPtgHr.png

接受的答案

SELECT
    `Name`,
    `Destination`, 
    `Type`,
    `Date`, 
    SEC_TO_TIME(SUM(TIME_TO_SEC(`Time_diff`))) as `Tot_Diff`
FROM (
    SELECT
        d.`Ime` as `Name`, 
        letD.`Destinacija_idDestinacija` as `Destination`, 
        l.`idLet` as idFlight,tip.`Tip` as `Type`,
        CAST(t.`Termin` as DATE) as `Date`, 
        timediff(Max(t.`Termin`), min(t.`Termin`)) as `Time_diff`
    FROM Letalo p
    INNER JOIN `Let` l 
        ON l.`Letalo_idLetalo` = p.`idLetalo`
    INNER JOIN `Let_Has_Destinacija` letD 
        on letD.`Let_idLet` = l.`idLet`
    INNER JOIN `Destinacija` d 
        on d.`idDestinacija` = letD.`Destinacija_idDestinacija`
    INNER JOIN `Termin` t 
        on t.`idTermin` = d.`Termin_idTermin`
    INNER JOIN `Tip_Destinacije` tip 
        on tip.`idTip_Destinacije` = `Tip_Destinacije_idTip_Destinacije` 
    WHERE p.Naziv = 'Falcon FX 3000'
    GROUP BY l.idLet
    ) as `main`

Answer 1

我相信这应该产生您描述的结果。基本上，它接受您拥有的查询，并将其用作子查询然后将时间差求和。

SELECT
    `Name`,
    `Destination`, 
    `Type`,
    `Date`, 
    SEC_TO_TIME(SUM(TIME_TO_SEC(`Time_diff`))) as `Tot_Diff`
FROM (
    SELECT
        d.`Ime` as `Name`, 
        letD.`Destinacija_idDestinacija` as `Destination`, 
        l.`idLet` as idFlight,tip.`Tip` as `Type`,
        CAST(t.`Termin` as DATE) as `Date`, 
        timediff(Max(t.`Termin`), min(t.`Termin`)) as `Time_diff`
    FROM Letalo p
    INNER JOIN `Let` l 
        ON l.`Letalo_idLetalo` = p.`idLetalo`
    INNER JOIN `Let_Has_Destinacija` letD 
        on letD.`Let_idLet` = l.`idLet`
    INNER JOIN `Destinacija` d 
        on d.`idDestinacija` = letD.`Destinacija_idDestinacija`
    INNER JOIN `Termin` t 
        on t.`idTermin` = d.`Termin_idTermin`
    INNER JOIN `Tip_Destinacije` tip 
        on tip.`idTip_Destinacije` = `Tip_Destinacije_idTip_Destinacije` 
    WHERE p.Naziv = 'Falcon FX 3000'
    GROUP BY l.idLet
    ) as `main`
GROUP BY `Name`,`Destination`,`Type`,`Date`;

如何减去日期，然后对上一个操作的结果求和

1 个答案: