Rows and cells

Each numbered row in a table forms a rule. The values in the cells of the row contain the conditions and actions of the rule:

To make rows in a decision table easier to read, you can merge cells with conditions that are common to more than one rule. In the following table, the Grade A cells of rows 1 and 2 have been merged into one cell:

You read the two rules as follows:

• Rule 1

  if
     all of the following conditions are true:
        - Grade is A
        - the amount of Loan is between 100,000 and 300,000,
  then...

• Rule 2

  if
     all of the following conditions are true:
        - Grade is A
        - the amount of Loan is between 300,000 and 600,000,
  then...

If a third row is added to the decision table, it can be shown in the following ways:

• It can have a different value for the first condition:

  	Grade	Loan
  		Min	Max
  1	A	100,000	300,000
  2		300,000	600,000
  3	B	600,000	900,000

• It can share the value for the first condition:

  	Grade	Loan
  		Min	Max
  1	A	100,000	300,000
  2		300,000	600,000
  3		600,000	900,000

Merged or split cells

In condition columns, you can merge or split the cells in subcolumns and change the operator. For example, the third row in the following table is also about Age, but it includes the operator foris more than, which takes only one value, instead of is between, which requires two values:

	Age
	Min	Max
1	18	25
2	26	40
3	>40

Partitioned cells

A partition is a group of cells in a condition column with a common cell next to them. In the following table, cells A and B in the Grade column each have a partition of cells in the Loan column.

	Grade	Loan		Insurance
		Min	Max	Rate	Required
1	A	<100,000			false
2		100,000	300,000	0.001	true
3		300,000	600,000	0.003	true
4		≥600,000		0.005	true
5	B	<100,000			false
6		100,000	300,000	0.0025	true
7		300,000	600,000	0.005	true
8		600,000	800,000
9		≥600,000		0.0075	true

Each numbered row in the table still forms a rule. Partitioning helps you compare rules with similar conditions, and find overlaps and gaps between values of the rules.

Empty cells

A row can contain empty cells. If an empty cell is in a condition column, the condition is always satisfied. If an empty cell is in an action column, the action cell is ignored.

In the following table, the first rule does not set an insurance rate.

	Grade	Loan		Insurance
		Min	Max	Rate	Required
1	A	<100,000			false
2		100,000	300,000	0.001	true
3		300,000	600,000	0.003	true
4		≥600,000		0.005	true