Simple Expressions

A simple expression specifies column, pseudocolumn, constant, sequence number, or null.

simple_expression::=

Text description of simple_expression

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.

The pseudocolumn can be either LEVEL, ROWID, or ROWNUM. You can use a pseudocolumn only with a table, not with a view or materialized view. NCHAR and NVARCHAR2 are not valid pseudocolumn datatypes.

Some valid simple expressions are:

employees.last_name 
'this is a text string'
10 
N'this is an NCHAR string'