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Help with SQL sub query

Author

Topic

jamie_pattison
Yak Posting Veteran

65 Posts

Posted - 2013-04-03 : 10:58:25

I have a select query which also has a sub query that im having problems with. My table for the Users structure is

ID
Department
Name
TeamLeaderID

Data is

ID Department Name TeamLeaderID
1 IT Tom NULL
2 Sheila 1
3 Ben 1
4 ADMIN Tony NULL

If the TeamleaderID is NULL it means they are a teamLeader.
If the TeamLeaderID has a value it means they are part of that IDs team.
For all child records the department is left blank and is retrieved from their TeamLeaderID

So in this case it means Shelia and Ben are in Tom's team (their TeamleaderID is 1 and ID 1 is Tom).

Here is my SELECT query

SELECT Department, Name FROM Users

This is nice and easy but now i need the departments from another table that has the userID saved against the record (ID from the above example), so my SQL is now like

SELECT
col1,
col2,
(SELECT Department FROM Users where ID =(CASE WHEN TeamLeaderID IS NULL THEN MyTable.ID ELSE MyTable.ID END)) As DepartmentName

FROM MyTable

What i am trying to return from my select is the department for every user. So if the TeamLeaderID is NULL then i want it to use the records ID (MyTable.ID in this case) to get the department name, otherwise if the myTable.ID has a value then to use that value (remember NULL means its a team leader and a value means its a member of the team, therefore in simple english i am getting the department name from the users name where the ID (If null would use the current records ID otherwise if it has a value it would use that value)

Could anyone help?

Thanks

russell
Pyro-ma-ni-yak

5072 Posts

Posted - 2013-04-03 : 11:05:33

this what you're after?

SELECT	a.name, isnull(a.department, b.department)
FROM	Users a
LEFT JOIN
	Users b
On	a.TeamLeaderID = b.id;

jamie_pattison
Yak Posting Veteran

65 Posts

Posted - 2013-04-03 : 11:42:30

Im not sure if thats what im after. I was hoping for a SQL Sub Query as i posted.

I have also tried the below syntax which again gives me the same problem

(SELECT Department FROM Users where ID = (SELECT ISNULL(TeamLeaderID, myTable.ID) As ID WHERE (ID=MyTable.ID)))

The problem i have here is that the department names for all child records are blank

russell
Pyro-ma-ni-yak

5072 Posts

Posted - 2013-04-03 : 12:51:04

Did you try running the code I posted?

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