Let me show you a small trick when is necesary to obtain some psedo-column (like rowid) or database function (like sysdate) .
If a direct mapping of those values is done, a error like this will happens:
For bypass this situation, a small trick could be used.
It is: just add ANY column from source table and comment it. From our previous example (image), it will look like:
That is all, just a small trick very usefull to mapping values from source that has no relation with a source column.
A query, a sequence, a function, any of this could be used with this technique.
See you all in the next post my friends!