Answer Posted / nagarjuna reddy

A pseudo column is a column but it is not physically existed
in the table.if we want to use these column by specifying
externally in select statement for projection or selection.
but we can't insert,delete and update pseudo columns.
some of pseudo columns are
1 ROWID
2 ROWNUM
3 LEVEL
4 CURRVAL
5 MEXTVAL
etc...

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