Getting Ambiguous Column Name Error - sql-server

Question

So I'm pretty new to this program and cannot figure out why I am getting this error.
Here is the qry.
SELECT policy_no,
phase_code,
sub_phase_code,
Duplicate_Indicator = CASE
WHEN Sum(1) <> 1 THEN 'DUPLICATE'
ELSE 'NOT DUPLICATE'
END
FROM qrypolicylistfornydefpremasset_re
RIGHT JOIN (SELECT TOP 100 PERCENT tblinsurance.policy_no,
tblinsurance.phase_code,
tblinsurance.sub_phase_code,
tblinsurance.prodtype,
tblinsurance.paid_to_date,
tblinsurance.val_date,
tblinsurance.issue_date,
tblinsurance.schednp,
Sum(tblinsurance.gross_annlzd_prem) AS
SumOfGROSS_ANNLZD_PREM,
Sum(tblinsurance.statnetpremium) AS
SumOfStatNetPremium,
Sum(tblinsurance.netdefpremium) AS
SumOfNetDefPremium,
Sum(tblinsurance.netdefextra) AS
SumOfNetDefExtra,
Sum(tblinsurance.netdefpremiumadj) AS
SumOfNetDefPremiumAdj,
Sum(tblinsurance.netdefextraadj) AS
SumOfNetDefExtraAdj,
NetvsGrossInd = CASE
WHEN
[netdefpremium] = [netdefpremiumadj]
THEN
'Net'
ELSE 'Gross'
END,
Sum(tblinsurance.amount_inforce) AS
SumOfAMOUNT_INFORCE,
Sum(tblinsurance.pua_face) AS
SumOfPUA_FACE,
Sum(tblinsurance.oyt_face) AS
SumOfOYT_FACE
FROM tblinsurance
WHERE ( ( ( tblinsurance.company_code ) = 'NL' )
AND ( ( tblinsurance.term_reason ) = 'A' )
AND ( ( tblinsurance. issue_date ) <= [val_date] ) )
GROUP BY tblinsurance.policy_no,
tblinsurance.phase_code,
tblinsurance.sub_phase_code,
tblinsurance.prodtype,
tblinsurance.paid_to_date,
tblinsurance.val_date,
tblinsurance.issue_date,
tblinsurance.schednp,
CASE
WHEN [netdefpremium] = [netdefpremiumadj] THEN
'Net'
ELSE 'Gross'
END
HAVING (( ( Sum(tblinsurance.netdefpremium) ) <> 0 )))Work
ON policy_no = qrypolicylistfornydefpremasset_re.policy_no
AND phase_code = qrypolicylistfornydefpremasset_re.phase_code
AND sub_phase_code =
qrypolicylistfornydefpremasset_re.sub_phase_code
GROUP BY policy_no,
phase_code,
sub_phase_code
Where I am getting the ambiguous colum name is on the Fields POLICY_NO, PHASE_CODE, SUB_PHASE_CODE, but only in the On and GROUP by at the end and the ones in the SELECT in the beginning.

Answer 1

well, you've got these fields in both
qryPolicyListforNYDefPRemAsset_Re
and in your subquery Work
so prefix them with the right table (or better, use aliases).
I prefixed with Work in SELECT and GROUP BY and JOIN I may be wrong for SELECT and GROUP BY (maybe you need q, alias for qryPolicyListforNYDefPRemAsset_Re) :I'm like Sql, your query is too ambiguous for me ;)
SELECT
Work.POLICY_NO,
Work.PHASE_CODE,
Work.SUB_PHASE_CODE,
Duplicate_Indicator = case when
SUM(1) <> 1 then 'DUPLICATE'
else 'NOT DUPLICATE'
end
FROM
qryPolicyListforNYDefPRemAsset_Re q
RIGHT JOIN
(SELECT top 100 percent
t.POLICY_NO,
t.PHASE_CODE,
t.SUB_PHASE_CODE,
t.ProdType,
t.PAID_TO_DATE,
t.VAL_DATE,
t.ISSUE_DATE,
t.SchedNP,
Sum(t.GROSS_ANNLZD_PREM) AS SumOfGROSS_ANNLZD_PREM,
Sum(t.StatNetPremium) AS SumOfStatNetPremium,
Sum(t.NetDefPremium) AS SumOfNetDefPremium,
Sum(t.NetDefExtra) AS SumOfNetDefExtra,
Sum(t.NetDefPremiumAdj) AS SumOfNetDefPremiumAdj,
Sum(t.NetDefExtraAdj) AS SumOfNetDefExtraAdj,
NetvsGrossInd = Case when [NetDefPremium]=[NetDefPremiumAdj] then 'Net' Else 'Gross' END,
Sum(t.AMOUNT_INFORCE) AS SumOfAMOUNT_INFORCE,
Sum(t.PUA_FACE) AS SumOfPUA_FACE,
Sum(t.OYT_FACE) AS SumOfOYT_FACE
FROM tblInsurance t
WHERE (((t.COMPANY_CODE)='NL') AND ((t.TERM_REASON)='A') AND ((t.ISSUE_DATE)<=[VAL_DATE]))
GROUP BY
t.POLICY_NO,
t.PHASE_CODE,
t.SUB_PHASE_CODE,
t.ProdType,
t.PAID_TO_DATE,
t.VAL_DATE,
t.ISSUE_DATE,
t.SchedNP,
Case when [NetDefPremium]=[NetDefPremiumAdj] then 'Net' Else 'Gross' END
HAVING (((Sum(t.NetDefPremium))<>0))
)Work
ON
Work.POLICY_NO = q.POLICY_NO AND
Work.qPHASE_CODE= q.PHASE_CODE AND
Work.SUB_PHASE_CODE = q.SUB_PHASE_CODE
GROUP BY
Work.POLICY_NO,
Work.PHASE_CODE,
Work.SUB_PHASE_CODE