[erp] and [dbo] are different schemas. Think of this as namespace in .Net, a logical separation of db object that object names accross different schemas do not collide. Another possible use of db schemas is permission assignment -- a user can have read/write permissions on [erp] schema but read-only on [dbo] or no access at all.

When creating and accessing objects in your db (tables, views, sps, etc.) you can prefix object name with optional schema name like CREATE TABLE erp.MyTable or CREATE PROC dbo.usp_MyProc

When schema is omitted from object names query planner uses default schema for the current db user which is dbo for sa login (server administrators) and this default resolution might fail for non-admins and/or lead to permission problems.

cheers,
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