A simple expression specifies a column, pseudocolumn, constant, sequence number, or null.
In addition to the schema of a user,
schema can also be "
PUBLIC" (double quotation marks required), in which case it must qualify a public synonym for a table, view, or materialized view. Qualifying a public synonym with "
PUBLIC" is supported only in data manipulation language (DML) statements, not data definition language (DDL) statements.
You can specify
ROWID only with a table, not with a view or materialized view.
NVARCHAR2 are not valid pseudocolumn data types.
Some valid simple expressions are:
employees.last_name 'this is a text string' 10 N'this is an NCHAR string'