A "pseudocolumn" is an expression that you can reference on an SQL statement. Two important pseudocolumns are
To learn how to use pseudocolumns, follow these steps:
rowidpseudocolumn contains data that Oracle is able to use to fetch a row directly from a database file. For example, here is the rowid of the IT Helpdesk department in the
rowidvalue we just retrieved to fetch the the IT Helpdesk department:
Departmentstable in the HR schema contains 27 departments. Let's imagine we only want to show the first 10 departments. The
rownumpseudocolumn can help us out. Here is the query to show the first 10 departments:
rowidpseudocolumn data, the
rownumdata is not stored on the database.