Conversion failed when converting the varchar value 'RN' to data type int - sql-server

Question

Im getting a conversion error when using the rownumber function on sql-server. I know plenty of similar threads have been posted but ive looked at them and they have different issues.
Conversion failed when converting the varchar value 'RN' to data type int.
It doesnt tell me where the problem is occuring. Does anyone have an idea of where it could be going wrong apart from the rownumber function?
This CTE is getting a previous transaction
, PRETRANSACTIONS AS (
SELECT DISTINCT
CONT.POH_ID AS POH_ID
,CONT.POH_POLICYNUMBER AS Contract_Number
,row_number() over (
partition by CONT.POH_ID
order by TRANS.txh_effectivedate desc
) AS 'RN'
,TXN_STAT.Txs_DESCRIPTION_I AS Transaction_Status_2
,TRANS.txh_effectivedate AS Transaction_Date_2
,TXN_DES.Txt_DESCRIPTION_I AS Transaction_Type_2
,TRX_RES.TRE_AMTPROCESSED AS Transaction_Amount_2
From Se2FAST.dbo.Cm_Opt_Poh_PolicyHdr_S CONT
JOIN BASE BASE
ON BASE.Poh_ID = CONT.POH_ID
INNER JOIN Se2FAST.dbo.Cm_Opt_Pch_PolicyCovHdr_S policyCov
ON CONT.Poh_ID = policyCov.Pch_POLICYHDRID
AND policycov.pch_sequence = 1
INNER JOIN [dbo].[Cm_Sys_Pst_PolicyStatus_I] PST
ON PST.Pst_ID_I = CONT.Poh_Status
LEFT JOIN se2Fast.DBO.CM_OPT_TXH_TRXHDR_S TRANS
ON TRANS.TXH_POLICYHDRID = CONT.POH_ID
AND TRANS.txh_effectivedate < ( SELECT TOP 1 TRAN1.txh_effectivedate
FROM se2Fast.DBO.CM_OPT_TXH_TRXHDR_S TRAN1
WHERE TRAN1.TXH_POLICYHDRID = CONT.POH_ID
ORDER BY txh_effectivedate DESC)
LEFT JOIN se2Fast.dbo.Cm_Opt_Tre_TrxRes_S AS TRX_RES
ON TRANS.Txh_ID = TRX_RES.Tre_TRXHDRID
LEFT JOIN se2Fast.dbo.Cm_Sys_Txt_TrxType_I TXN_DES
ON TRANS.Txh_TRXTYPEID = TXN_DES.Txt_ID_I
--AND TXN_DES.Txt_DESCRIPTION_I NOT IN (
--'Anniversary','Monthiversary','Quarterversary','Calendar Year End')
--AND TXN_DES.Txt_DESCRIPTION_I IS NOT NULL
LEFT JOIN se2Fast.dbo.Cm_Sys_Txs_TrxStatus_I TXN_STAT
ON Trans.Txh_TRXSTATUS = TXN_STAT.Txs_ID_I
AND TXN_STAT.Txs_DESCRIPTION_I = 'Completed'
WHERE 'RN' = 2
)

Answer 1

WHERE 'RN' = 2 is comparing two values, the string 'RN' and the integer 2. When SQL Server parses the expression, it is attempting to convert the literal value 'RN' to a numeric value to perform the integer comparison. Obviously, RN cannot be converted to a numeric value so you are getting an error.
In SQL Server, aliases are materialized after the WHERE/GROUP/HAVING clauses, but before the ORDER BY clause. This means you can't use the alias within the filter of the query it was assigned. You need to generate your column alias in a subquery before you can use it in a comparison.
It looks like you've mixed up your query. You've started as CTE named 'PRETRANSACTIONS', but then you've tried to alias it as a column after the closing parenthesis, AS 'RN'. A CTE must be referenced in the FROM before you can use the columns in the SELECT. If this is just a column expression, get rid of 'PRETRANSACTIONS AS' at the beginning.
WITH PRETRANSACTIONS AS (
SELECT DISTINCT
CONT.POH_ID AS POH_ID
,CONT.POH_POLICYNUMBER AS Contract_Number
,row_number() over (
partition by CONT.POH_ID
order by TRANS.txh_effectivedate desc)
AS RN)
SELECT RN,
TXN_STAT.Txs_DESCRIPTION_I AS Transaction_Status_2
,TRANS.txh_effectivedate AS Transaction_Date_2
,TXN_DES.Txt_DESCRIPTION_I AS Transaction_Type_2
,TRX_RES.TRE_AMTPROCESSED AS Transaction_Amount_2
From Se2FAST.dbo.Cm_Opt_Poh_PolicyHdr_S CONT
JOIN BASE BASE
ON BASE.Poh_ID = CONT.POH_ID
JOIN PRETRANSACTIONS
ON BASE.POH_ID = PRETRANSACTIONS.POH_ID
INNER JOIN Se2FAST.dbo.Cm_Opt_Pch_PolicyCovHdr_S policyCov
ON CONT.Poh_ID = policyCov.Pch_POLICYHDRID
AND policycov.pch_sequence = 1
INNER JOIN [dbo].[Cm_Sys_Pst_PolicyStatus_I] PST
ON PST.Pst_ID_I = CONT.Poh_Status
LEFT JOIN se2Fast.DBO.CM_OPT_TXH_TRXHDR_S TRANS
ON TRANS.TXH_POLICYHDRID = CONT.POH_ID
AND TRANS.txh_effectivedate < ( SELECT TOP 1 TRAN1.txh_effectivedate
FROM se2Fast.DBO.CM_OPT_TXH_TRXHDR_S TRAN1
WHERE TRAN1.TXH_POLICYHDRID = CONT.POH_ID
ORDER BY txh_effectivedate DESC)
LEFT JOIN se2Fast.dbo.Cm_Opt_Tre_TrxRes_S AS TRX_RES
ON TRANS.Txh_ID = TRX_RES.Tre_TRXHDRID
LEFT JOIN se2Fast.dbo.Cm_Sys_Txt_TrxType_I TXN_DES
ON TRANS.Txh_TRXTYPEID = TXN_DES.Txt_ID_I
--AND TXN_DES.Txt_DESCRIPTION_I NOT IN (
--'Anniversary','Monthiversary','Quarterversary','Calendar Year End')
--AND TXN_DES.Txt_DESCRIPTION_I IS NOT NULL
LEFT JOIN se2Fast.dbo.Cm_Sys_Txs_TrxStatus_I TXN_STAT
ON Trans.Txh_TRXSTATUS = TXN_STAT.Txs_ID_I
AND TXN_STAT.Txs_DESCRIPTION_I = 'Completed'
WHERE PRETRANSACTIONS.RN = 2
On a separate note, never use DISTINCT in the same set as ROW_NUMBER. ROW_NUMBER generates a unique number for every row, therefore every row is distinct. All that will do is add sorting overhead without eliminating any rows. You can use RANK or DENSE_RANK instead.

Answer 2

dont use 'RN', just RN without quotes.

Answer 3

You are getting this error because you are comparing the Text value 'RN' with an Integer value 2 in the where clause. But since 'RN' is a column and you want to return all the files that have a value 2 in the field 'RN' instead of
WHERE **'RN'** = 2
just type
WHERE RN = 2
RN without quotes as it is the name of the column.