factor 

factor specifies how the values are determined that are to be linked in an expression by means of arithmetic operators.

Syntax

<factor> ::= [<sign>] <value_spec> | [<sign>] <column_spec>
| [<sign>] <function_spec> | [<sign>] <set_function_spec> | <expression>

sign, value_spec, column_spec, function_spec, set_function_spec, expression