dbo user is the database owner and cannot be deleted from the database. Members of the
sysadmin server role are mapped to the
dbo user in each database, which allows them to administer all databases. Objects owned by
dbo that are part of the
dbo schema can be referenced by the object name alone. When an object is referenced without a schema name, SQL Server first looks for the object in the default schema for the user that is connected. If the object is not in the user’s default schema, the object is retrieved from the
dbo schema. Users can have a default schema that is set to
Schemas and their relationship to users are discussed in more detail in the section “User/Schema Separation,” later in this chapter.