Sql syntax: 1 til mange . mange til en

Hey Tiqtak !

For det første tror jeg godt at du kan udelade ID i din employee_workgroup-tabel, da du har en sammensat fremmednøgle, og den derfor bliver overflødig.

Dvs. at din tabel-struktur (mener jeg) bør se ud som flg:

Employee:
  ID

employee_workgroup    <--- du fungerer som en pointer-tabel !
  employeeID
  workgroupID

Workgroup:
  ID
  navn
  beskrivelse


men jeg vil umiddelbart skyde på at din select skal se ud ala:

SELECT w.id, w.navn, w.beskrivelse
FROM employee e, employee_workgroup ew, workgroup w
WHERE e.id = ew.employeeID
AND ew.workgroupID = w.id
AND e.id = 1    <--- her indsætter du så den employee du vil have oplysninger om.


...i think...

If you are not interested in other information for the employee than the employee id then you dont need the employee table as the ID is in the employee_workgroup table

SELECT employee_workgroup.EmployeeID, workgroup.ID, workgroup.navn, workgroup.beskrivelse
FROM workgroup INNER JOIN employee_workgroup ON workgroup.ID = employee_workgroup.workgroupID

and if you want the empployee information then you will need all three tables

SELECT Employee.*, employee_workgroup.EmployeeID, workgroup.ID, workgroup.navn, workgroup.beskrivelse
FROM Employee INNER JOIN (workgroup INNER JOIN employee_workgroup ON workgroup.ID = employee_workgroup.workgroupID) ON Employee.ID = employee_workgroup.EmployeeID

this is actually a many-to-many relationship which always needs three tables

the syntax can vary depending on which dB you are using, this should work in Access and SQL server

www.hotweb.tk - den kan faktisk bruges til lidt af hvert (:



Så bare chek den ud, der er nok noget du kan bruge -


- www.hotweb.tk

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where can I find help on this question?

tak