Simple Expressions

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

simple_expression::=

Description of the illustration simple_expression.gif

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 optional PRECEDING and INITIAL keywords following column are valid only when you are issuing a versions query.

You can specify ROWID only with a table, not with a view or materialized view. NCHAR and NVARCHAR2 are not valid pseudocolumn datatypes.

See Also:

Chapter 3, "Pseudocolumns" for more information on pseudocolumns and subquery_factoring_clause for information on query_name

Some valid simple expressions are:

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