We've found it out later. RVSP code is in Roles database table.
[dbo].[Roles]
([PortalID]
,[RoleName]
,[Description]
,[ServiceFee]
,[BillingFrequency]
,[TrialPeriod]
,[TrialFrequency]
,[BillingPeriod]
,[TrialFee]
,[IsPublic]
,[AutoAssignment]
,[RoleGroupID]
,[RSVPCode]
,[IconFile]
,[CreatedByUserID]
,[CreatedOnDate]
,[LastModifiedByUserID]
,[LastModifiedOnDate]
,[Status]
,[SecurityMode]
,[IsSystemRole])