Hi @Prabhat Singh ,
CDC is a schema that has the same name as the user CDC, just like dbo, guest.
Agree with Erland that You add users to roles (and db_owner is a role), not schemas.
Here are some tips to get it more clear:
Server login: means a user who has permission to login to a server.
Server role: means a fixed set of server users, of which there are nine by default.
Database user: means a user who has permission to be able to operate a database.
Database roles: refers to a fixed set of database roles with certain privileges.
Database schema: means a container for database objects.
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