SQL查询根据单独的查询结果联接多个表

Question

I am trying to find the right SQL query to join multiple tables together based upon a separate query..

I query the 'Titles' table to get the 'TitleId' - I then need to query 'Titles_Hardware' and 'Titles_Software' to match the 'Title Id' to the 'Hardware ID'/'Software Id'.

I then need to take those 'Hardware Ids' and 'Software Ids' to query the 'Hardware' and 'Software' tables to grab the friendly names of the Hardware and Software that particular user needs.

I have tried subqueries/cross join and many other queries I found on this site - none seem to give me what I need.. any suggestions would be absolutely amazing!

Outline of the database (tables are shown in italics)..

Answer 1

This query should do what you want, but it's not clear what you mean by "join multiple tables together based upon a separate query..". Here I just treated everything as tables.

SELECT t.TitleName, t.TitleId, h.HardwareName, s.SoftwareName
FROM Titles t
INNER JOIN Title_Hardware th ON th.TitleId = t.TitleId
INNER JOIN Hardware h ON h.HardwareId = th.HardwareId
INNER JOIN Title_Software ts ON ts.TitleId = t.TitleId
INNER JOIN Software s ON s.SoftwareId = ts.SoftwareId
WHERE t.TitleId = 'bleh'

EDIT

From the comments, you need three queries to get what you want:

SELECT t.TitleName
FROM Titles t
WHERE t.TitleId = 'bleh'

SELECT h.HardwareName
FROM Titles t
INNER JOIN Title_Hardware th ON th.TitleId = t.TitleId
INNER JOIN Hardware h ON h.HardwareId = th.HardwareId
WHERE t.TitleId = 'bleh'

SELECT s.SoftwareName
FROM Titles t
INNER JOIN Title_Software ts ON ts.TitleId = t.TitleId
INNER JOIN Software s ON s.SoftwareId = ts.SoftwareId
WHERE t.TitleId = 'bleh'

Answer 2

It should just be a simple multi-level join

SELECT TitleName, HardwareName, SoftwareName
FROM Titles
INNER JOIN Titles_Hardware
ON Titles.TitleId = Titles_Hardware.TitleId
INNER JOIN Titles_Software
ON Titles.TitleId = Titles_Software.TitleId
INNER JOIN Hardware
ON Hardware.HardwareId = Titles_Hardware.HardwareId
INNER JOIN Software
ON Software.SoftwareId = Titles_Software.SoftwareId
WHERE Titles.TitleId = {something}

Answer 3

You should be able to use a series of INNER JOINs to achieve your goal, like :

select 
    t.titleName,
    h.hardwareName,
    s.softwareName
from titles t
inner join titles_hardware th on th.titleId = t.titleId
inner join hardware h on h.hardwareId = th.hardwareId
inner join titles_sotfware ts on ts.titleId = t.titleId
inner join software s on s.softwareId = ts.softwareId
where t.titleId = 'foo'

Answer 4

Maybe a UNION could work for you

DECLARE @TitleName VARCHAR(100) = 'The Boss Lady';

SELECT hard.HardwareName AS Name, 'hard' as TitleType, tit.TitleName
FROM Titles tit
JOIN Titles_Hardware tithard ON tithard.TitleId = tit.TitleId
JOIN Hardware hard ON hard.HardwareId = tithard.HardwareId
WHERE tit.TitleName = @TitleName

UNION ALL

SELECT soft.SoftwareName, 'soft', tit.TitleName
FROM Titles tit
JOIN Titles_Software titsoft ON titsoft.TitleId = tit.TitleId
JOIN Software soft ON soft.SoftwareId = titsoft.SoftwareId
WHERE tit.TitleName = @TitleName