${variable||value||type||options}$

This is the most flexible syntax as it supports setting a name, default value, data type, and other options. Check the DbVisualizer Variables section for details.

A DbVisualizer variable can be used anywhere in the SQL as the specified value replaces the variable definition as a literal (unless a data type is specified; with a data type, its behavior is exactly the same as for Named Parameter Markers).

select * 
from   EMPLOYEE 
where  FIRST_NAME like '${First Name||Phil}$'
and    AGE > ${Age||20}$

The variable identifiers, ${...}$ can be modified in Tools->Tool Properties and in the General / Variables category.