Physical Table Aliases
After you import the database tables into the physical layer, you can create aliases for the table.
An alias is a physical object stored in the physical layer. The other two types are opaque view and physical table.
Why do we need to create alias?
First let’s look at SQL.
An alias is given to a table in a SQL, so you can refer it in other places to avoid confusing.
It is required, if you refer the table more than once in a SQL statement.
That is the same reason of creating physical table aliases in the BI metadata.
If a dimension table can be used as a role playing dimension, a fact table may join to the table using different foreign keys, you need to give the table a different alias for different roles.