Query : select tblcdslclmast.cClientboid as cClientboid,tblcdslclmast.nFirmnumber as nFirmnumber,tblcdslcompany.nDpid as nDpid from tblcdslclmast,tblcdslcompany where tblcdslcompany.nFirmnumber=tblcdslclmast.nFirmnumber and tblcdslclmast.cclientstatus='A' And tblcdslclmast.cLDClientcode = 'S1529' Is NSDL C Connection string : Data Source=;User Id=CLLVL;Password=;Connection Lifetime = 120; Connection Timeout = 60; Query Result : Error :- ORA-12154: TNS:could not resolve the connect identifier specified / Data Source=;User Id=CLLVL;Password=;Connection Lifetime = 120; Connection Timeout = 60;