The alias should be on the column (i.e., inside the convert function). Also, when you use VARCHAR, always specify a lenght.SELECT SOL_ID + CUST_ID + TDS_CERT_NUM + CONVERT(VARCHAR(512), TRAN_DATE) + BANK_ID
FROM SSISLOGS..tds_new a
WHERE NOT EXISTS (
SELECT 1
FROM DWH_STAGING..tds
WHERE SOL_ID + CUST_ID + TDS_CERT_NUM + CONVERT(VARCHAR(512), TRAN_DATE) +
BANK_ID = a.sol_id + a.cust_id + a.tds_cert_num + CONVERT(VARCHAR(512), a.TRAN_DATE)
+ a.bank_id
)