A "pseudocolumn" is an expression that you can reference on an SQL statement. It is not a column that is stored on a table. Pseudocolumns have a variety of applications including hierarchical queries, row metadata and sequences. In this topic I will show you how sequence data can be obtained from pseudocolumns.
To learn how to use pseudocolumns, follow these steps:
employees_seq. The current value of the sequence can be determined by executing this query:
currval. You can also display the
nextvalpseudocolumn. Whenever you reference this column on an SQL statement the pseudocolumn will increment the sequence and return the new value.