Question

I got a join select statement and i only need the last modified field in the second table. here’s the select statement that i have now:

SELECT  NOM,PRENOM,OEDP.NUM_EMP,N_A_S,SIT_STATUT,PERMIS,DATE_EMBAUCHE,ADRESSE1,VILLE1,PROVINCE1,CODE_POSTAL1,TEL_RESIDENCE
FROM    ODS_EMPLOYE_DOSSIER_PERSONNEL AS OEDP
JOIN    ODS_SITUATION_POSTE AS OSP
ON      OEDP.NUM_EMP = OSP.NUM_EMP
WHERE   SIT_DATE_CHG = MAX(SIT_DATE_CHG)
ORDER BY
        OEDP.NUM_EMP

i got the folowing erreur msg :

An aggregate may not appear in the WHERE clause unless it is in a subquery contained in a HAVING clause or a select list, and the column being aggregated is an outer reference.

Answer 1

SELECT  NOM,PRENOM,OEDP.NUM_EMP,N_A_S,SIT_STATUT,PERMIS,DATE_EMBAUCHE,ADRESSE1,VILLE1,PROVINCE1,CODE_POSTAL1,TEL_RESIDENCE
FROM    ODS_EMPLOYE_DOSSIER_PERSONNEL AS OEDP
CROSS APPLY 
        (
        SELECT  TOP 1 *
        FROM    ODS_SITUATION_POSTE AS OSP
        WHERE   OEDP.NUM_EMP = OSP.NUM_EMP
        ORDER BY
                SIT_DATE_CHG DESC
        ) OSP
ORDER BY
        OEDP.NUM_EMP

Actually, there are several methods to do this, and their efficiency depends on how the data are distributed across the tables.

See this article in my blog for comparison of these methods:

• SQL Server: Selecting records holding group-wise maximum