Adding and Manipulating Decision Table Columns

Decision table columns determine the names and types of the table's inputs and outputs.

Recall that decision tables can have two column types:

Simple columns: whereby a match is checked by comparing the input value to the corresponding value in the table
Range columns: where a match is checked by comparing the input value to a range defined in the table.

Columns and their values are managed in the Column Manager, launched by clicking Open Column Manager in the decision table editor.

To add a simple input column, type a suitable name in the first empty Header field, select Simple in the Type drop-down list and click Add in the last column.
To add a range column, type a suitable name in the first empty Header field, select Range in the Type drop-down list, select an item in the Operator drop-down list and click Add in the last column.
The lower and upper bounds of range keys are added as later edits to table rows.
The Operator field can be set to one of four values:
- < .. <=: The range does not include its lower bound but includes its upper bound.
- <= .. <: The range includes its lower bound but does not include its upper bound.
- < .. <: The range does not include either its lower bound or its upper bound.
- <= .. <=: The range includes both its lower bound and its upper bound.
The figure shows the result of adding a simple column, a range column and an output value to a new table. Note that the value selected as an Operator contains essential whitespace:
```
[operator][space]..[space][operator] 
```
This is especially important to bear in mind if you decide to edit a decision table in a text editor as a CSV file (see Editing Decision Tables as CSV Files).

The Decision Table Column Manager
Column Manager edits that have not been saved are denoted by an asterisk(*) following the column ids in the first column. Click Update to save them. Click Close to dismiss the Column Manager - a warning appears if you have unsaved changes.