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Calculated Columns


Calculated columns were added in GanttProject 3.3. This article explains some non-trivial aspects of using calculated columns in GanttProject.

Calculated column is a task property, or a column in the task table, with the value that is calculated from the values of other columns.

You can turn any task custom column into calculated using "Value is calculated" checkbox and "Value expression" field in the column properties pane of the Column Manager dialog.

Value expression

The value expression is an SQL expression which one would write in SELECT clause of a query against Task table with the following columns:

name type description
uid text immutable long task identifier, unique across all projects unless a project is copied
id int task number, visible as ID in the user interface, unique in the scope of a single project
name text task name
color text RGB value of a task color in CSS format (e,g, #ffca28)
is_milestone boolean flag indicating if a task is a milestone or not
is_project_task boolean flag indicating if a task is a "project task"
start_date date task start date
end_date date task end date
duration int task duration in days
completion int task completion, percentage value in [0..100] interval
earliest_start_date date task earliest start date, if any
priority text task priority value, one of {'0', '1', '2', '3', '4'} to be discussed
web_link text task web link value
cost_manual_value decimal task cost, if set explicitly, null otherwise
is_cost_calculated boolean flag indicating if task cost is calculated or set manually
notes text task notes
cost decimal task cost value, calculated or set explicitly

Value expressions are evaluated by the real SQL database engine. We use H2 database, and you may use all standard SQL operations and functions implemented in h2. Pay attention that equality operator in SQL is =, and string concatenation operator is ||.


Calculated columns can be defined only for tasks and value expressions may use only the standard task properties described above.