Learn about the logical columns that exists in oracle database with example queries.
Pseudo columns are nothing but logical columns which behaves like a physical columns in database.
Means Pseudo columns behaves like a table columns but is not actually stored in the table.
You can select from pseudo-columns, but you cannot insert, update, or delete their values.
A pseudo-column is also similar to a function without arguments.
The examples of Pseudo columns are –
- rowid
- currval and nextval
- versions_xid
- versions_operation
- versions_startscn
- versions_endscn
- sysdate
- systimestamp
- rownum
- ora_rowscn
- object_value
- level
- user
Now our main focus is on rowid, row num, currval, and nextval, level pseudo columns.