PL/SQL equivalent of T-SQL - "group function is not allowed here"

Question

Hi all, hope someone can give me a hand as I'm pretty stuck! I have been trying to convert some MS SQL Server T-SQL statements into Oracle PL/SQL and am stuck on the below one:
SELECT
CA.AssessmentID,
(SELECT ProductName + ISNULL(' - ' + PrincipalBenefit,'')
FROM rptPolicySnapshot WHERE PolicyID = MAX(CA.PolicyID)
AND SnapshotID = 1),
MAX(CA.PolicyID)
FROM rptClaimInvoiceLineSnapshot CIL
INNER JOIN rptClaimAssessmentSnapshot CA
ON CIL.AssessmentID = CA.AssessmentID
AND CIL.SnapshotID = CA.SnapshotID
WHERE CIL.SnapshotID = 1
GROUP BY CA.AssessmentID
This works fine in MSSQL but returns the below error in Oracle:
'ORA-00934: group function is not allowed here'
If I take out the subquery the query works fine.
Any ideas as to the syntax? I am new to Oracle so not sure as to how I should go about writing this.
Thanks in advance!
Leo

Answer 1

WITH x AS (SELECT   ca.assessmentid,
                    MAX (ca.policyid) policy_id
           FROM rptclaiminvoicelinesnapshot cil
                INNER JOIN rptclaimassessmentsnapshot ca
                    ON cil.assessmentid = ca.assessmentid
                   AND cil.snapshotid = ca.snapshotid
           WHERE cil.snapshotid = 1
           GROUP BY ca.assessmentid
SELECT x.assessment_id,
       x.policy_id,
       productname + decode(principalbenefit,null,null,' - ' || principalbenefit ) prodname
FROM   rptpolicysnapshot, x
WHERE  policyid = x.policy_id
AND    snapshotid = 1I think that's in the neighbourhood.