Column specification (column spec) 

A column specification ( column spec ) specifies a column in a table.

Syntax

<column spec> ::= <column name> | <table name>.<column name>
| <reference name>.<column name> | <result table name>.<column name>

column name, table name, reference name, result table name

Explanation

For all names consisting of several identifiers separated by a ".", any number of blanks can be specified before and after the dot.