Select in Inner Join problem

Do you realise your sub query (if it worked) would return only one record?  Being an inner join then your entire query would only return 1 record.  Is this the desired result?

Try something like this.  I'm not understanding your query, but this may help you understand what I mean.

SELECT          *
FROM          v_AnalogHistory
INNER JOIN     (SELECT NaedChange.NaedID,RPMSetupProd.dbo.Naed.Name,MAX(NaedChange.Datetime)
          FROM RPMViewProd.dbo.NaedChange AS NaedChange
          LEFT OUTER JOIN RPMSetupProd.dbo.Naed ON RPMSetupProd.dbo.Naed.ID = NaedChange.NaedID
          INNER JOIN v_AnalogHistory a ON Naed.Datetime <= a.Datetime
          WHERE NaedChange.Line = 'Ligne 3' GROUP BY NaedChange.NaedID,RPMSetupProd.dbo.Naed.Name) AS Naed ON Naed.Datetime <= v_AnalogHistory.Datetime
WHERE           v_AnalogHistory.Tagname = 'L1_Sealer_TEMP_F'
          AND v_AnalogHistory.Datetime >= DateAdd(n,-15,getDate())

Sorry.  I didn't notice the <= in the join statement.  I've never seen anybody construct a join with a <= before.

My subquery that I used, may give you the results that you where looking for.  Using the group by and max(date), you may be able to do this without using a sub query.

<= v_AnalogHistory.Datetime

You can't put that part in the sub query.  It has to be part of the join syntax.

SELECT *
FROM v_AnalogHistory
INNER JOIN     (  SELECT NaedChange.NaedID,NaedChange.Datetime,RPMSetupProd.dbo.Naed.Name
                FROM RPMViewProd.dbo.NaedChange AS NaedChange
                LEFT OUTER JOIN RPMSetupProd.dbo.Naed ON RPMSetupProd.dbo.Naed.ID = NaedChange.NaedID
                WHERE NaedChange.Line = 'Ligne 3'
                ORDER BY NaedChange.Datetime DESC) AS Naed ON Naed.Datetime <= v_AnalogHistory.Datetime And <= v_AnalogHistory.Datetime
WHERE           v_AnalogHistory.Tagname = 'L1_Sealer_TEMP_F'
          AND v_AnalogHistory.Datetime >= DateAdd(n,-15,getDate())

Sorry again.  That should have read:

SELECT *
FROM v_AnalogHistory
INNER JOIN     (  SELECT NaedChange.NaedID,NaedChange.Datetime,RPMSetupProd.dbo.Naed.Name
                FROM RPMViewProd.dbo.NaedChange AS NaedChange
                LEFT OUTER JOIN RPMSetupProd.dbo.Naed ON RPMSetupProd.dbo.Naed.ID = NaedChange.NaedID
                WHERE NaedChange.Line = 'Ligne 3'
                ORDER BY NaedChange.Datetime DESC) AS Naed ON Naed.Datetime <= v_AnalogHistory.Datetime And NaedChange.Datetime <= v_AnalogHistory.Datetime
WHERE           v_AnalogHistory.Tagname = 'L1_Sealer_TEMP_F'
          AND v_AnalogHistory.Datetime >= DateAdd(n,-15,getDate())

I am now studying and trying to make your suggested queries work, this may take a while but don't worry I will come back with the results.

I'll try to explain the purpose of my query to clear things up, this will be complicated to explain in text so please bare with me.

I have a view called v_AnalogHistory witch returns something that looks like this:

Datetime            Value
----------------      -----
2004/03/26 07:45      987
2004/03/26 07:46      800
2004/03/26 07:53      958
2004/03/26 08:21      902
2004/03/26 08:34      905

I a have a table called NaedChange wich looks like this:

Datetime            NaedID
----------------      -----
2004/03/23 14:23      1
2004/03/26 08:00      2

I have a table called Naed that looks like this:

ID      Name      LampType
--      -----      -----------
1      21345      Regulier
2      21346      Suntan Full


I want to do a query that would return this:

Value      Naed.ID            Naed.Name      Naed.LampType
-----      -------             ---------            -------------
987      1            21345            Regulier
800      1            21345            Regulier
958      1            21345            Regulier
902      2            21346            Suntan Full
905      2            21346            Suntan Full


In ohter words I want all the values each associated with the naed that was active at that time, the last one entered before the date of the value.
After that I want to be able to add conditions like Naed.ID = 1 or Naed.LampType = 'Regulier' so that only the values with a correct naed or correct lampType would be return by the query.

This is what my query that I posted in my question was suppose to do but I can't find a syntax to fit my logic.

IT WORKS!

Thanks alot Lowfatspread!