Defining New Rules in the Rule Set :: SAS(R) Decision Manager 2.2: User's Guide

Add a New Rule

Open the rule set where you want to add the new rule.
Select the Rules page.

The default view of a rule set is the horizontal view. In the horizontal view, the terms used by the rules are displayed across the top of the rule set editor, and the editor has one row for each rule in the rule set. To switch to the vertical view, select Vertical from the menu in the toolbar above the editor. In the vertical view, the terms used by the rules are displayed in the left column, and the editor has one column for each rule in the rule set.
Click .
Add any additional terms that the new rule requires, and add expressions for the new rule in the table cells in the rule editor. See Define Expressions for a Rule for more information.
(Optional) Change the order of the new rule. The rule order, in addition to the IF, ELSE, or OR keyword (see Controlling Which Conditions Are Evaluated), controls how rules are evaluated within the rule set.

Tip
You can also change the order of the rules later by right-clicking on a rule and selecting either Reorder or Swap. See Change the Order of Rules in a Rule Set for more information.
(Optional) Modify the name of the new rule on the Rule Details tab. Rule names are limited to 100 characters and must be unique within a rule set.
(Optional) Clear the Record rule-fired data check box on the Rule Details tab if you do not want a rule-fired record to be written each time this rule fires.
(Optional) Enter a description for the new rule on the Rule Details tab.
Click .

Define Expressions for a Rule

To define the expressions for a rule:

Add any additional terms to the rule set editor that the rule requires. You can add a single term in one of two ways:
- Right-click on the term in the Vocabulary pane, and select either Use as condition term or Use as action term.
- Drag the term from the Vocabulary pane onto a column in the rule set editor.
You can also add multiple terms at the same time.
- If the terms that you want to add to the table all belong to the same entity, you can add the entire entity to the table in the same way that you add a single term. Note that an entity can contain dozens of terms, and you cannot undo this operation after you have added the terms. You must delete terms one at a time.
- If the terms do not all belong to the same entity, select the terms and drag them onto the table, or use the pop-up menu as you would for a single term. To select a consecutive set of terms, click on the first term, hold down the Shift key, and click on the last term. To select nonconsecutive terms, hold down the Ctrl key, and click on each term that you want to select.
For example, if your rule is If balance < 100 then risk = "high", the condition term is balance and the action term is risk.

Tip
By default, terms are listed in the table in alphabetical order. You can reorder the terms by dragging the terms in the column or row headings.

Tip
You can add new entities and terms by clicking in the Vocabularies pane. You can also edit existing entities and terms by right-clicking on the entity or term and selecting the appropriate option. See Create New Entities and Create New Terms for more information.
(Optional) Select the operator for the rule. The default operator is IF. See Controlling Which Conditions Are Evaluated for more information.
For each term that is used in the new rule, specify the expression that applies to that term in the row or column for the new rule. For example, if the rule is If balance < 100 then risk = "high", the expression for balance is < 100, and the expression for risk is = "high".

Expressions can be up to 1024 characters long. They can contain numeric constants, character strings, vocabulary terms, operators, and SAS DS2 functions.

Condition expressions can contain the LOOKUP function, and action expressions can contain the LOOKUPVALUE function. However, if the expression contains the LOOKUP or LOOKUPVALUE function, then the expression cannot contain anything else.

Tip
A rule that does not have a condition expression always executes.

Tip
If a rule has been assigned the IF operator and a condition expression but it does not have an action expression, the condition expression is evaluated, but no action is taken. (See Controlling Which Conditions Are Evaluated for information about the IF operator.)

You can enter expressions directly into the decision table, or you can use the Expression Editor to create and edit expressions. To open the Expression Editor, click in the table cell, and select .

As you enter expressions into each cell, SAS Decision Manager displays the rule conditions and actions, including the operators and term names that are added by SAS Decision Manager, on the Rule Details tab.(See Terms and Operators Added by SAS Decision Manager.) For example, suppose you enter the following rule in the editor:

SAS Decision Manager displays the following expressions on the Rule Details tab.
For more information about entering expressions, see the following topics:
Click to save the rule set. SAS Decision Manager validates the syntax of the expressions. If it does not detect any problems, it saves the rule set. See Validate the Expressions in a Rule Set for more information.

Controlling Which Conditions Are Evaluated

You add conditional processing within a rule set by using the IF, ELSE, and OR operators. By default, rules are assigned the keyword IF, which means that the rule’s condition is evaluated regardless of the results of previous rules. You can change this outcome by changing the operator for a rule to ELSE or OR.

If you set a rule’s operator to ELSE, then the rule’s condition is evaluated only if the previous rule’s condition evaluated to false. For example, given the rule set shown the following display, if Order_Quanitity is 12, the condition for rule 1 evaluates to false, the condition for rule 2 evaluates to true. Therefore, the action for rule 2 is executed. The conditions for rules 3 and 4 are not evaluated.

Image Showing Rule One as Order_quantity <= 5 and Rule Two as order_quantity >=10 and <=15

Use the OR operator to break up very long condition expressions into multiple condition expressions and to execute the same action expression for each of the conditions. If you assign the OR operator to a rule, then you cannot enter an action expression for the rule. If any of the conditions evaluate to true, SAS Decision Manager executes the action of the last rule that was assigned the IF or ELSE operator. When you have several consecutive rules that are all assigned the OR operator, only the action for the first rule whose condition evaluates to true is executed. The conditions for the remaining consecutive OR rules are not evaluated.

For example, suppose you have a very long condition expression such as the one shown in the following display.

Image Showing Very Long Condition Expression with Multiple Clauses

As shown in the next display, you can break this expression into four different rules and use the OR operator, which makes the rule much easier to read and edit.

Image Showing Four Separate Rules that Duplicate the Original Logic

For example, in the following rule set, rules 1 though 4 use the action expression that is defined for rule 1. Rules 5 through 7 use the action expression that is defined for rule 5.

Rule Set That Defines Seven Rules in Two IF Blocks

Display Showing Seven Rules with Action Expressions Assigned to Rules 1 and 5 only

An IF block is a series of rules that begins with an IF operator and extends up to but does not include the next IF operator. In the rule set shown in Rule Set That Defines Seven Rules in Two IF Blocks, rules 1 to 4 are an IF block and rules 5 to 7 are a second IF block.

Note: A rule that does not have a condition expression must be the last rule in an IF block.

Using the Expression Editor

Open the Expression Editor

To open the Expression Editor, click in a cell in the rule set editor, and click Expression Editor

.

The Lookup tab is available only for condition terms, and the Lookup Value tab is available only for action terms. Buttons for some of the operators might be disabled depending on the data type of the term, and because action expressions can be assignment expressions only.

Expression Tab for an Action Term

Build an Expression in the Expression Editor

To define expressions that do not use the LOOKUP or LOOKUPVALUE functions, enter the expression on the Expression tab. Click on the operators, vocabulary terms, and domain values as needed to add them to the expression. The Expression Editor builds the expression in the top field. To add date constants to the expression, click select a date

. To add numeric constants, character strings, or functions to the expression, enter them directly into the top field. (Remember to use the correct punctuation. See Punctuation for Data Values.) When you are finished, click OK. The Expression Editor validates the syntax of the expression. If the editor does not find any problems, it adds the expression to the cell in the table where you opened the editor. You can click Validate at any time to check the syntax of the expression that you are building.

To build an expression that uses the LOOKUP or LOOKUPVALUE functions, switch to the Lookup or LookupValue tabs. You can enter the LOOKUP function in condition expressions only, and you can enter the LOOKUPVALUE function in action expressions only. See Specify the LOOKUP Function in the Expression Editor and Specify the LOOKUPVALUE Function in the Expression Editor for more information.

Specify the LOOKUP Function in the Expression Editor

To use the Expression Editor to enter the LOOKUP function, click the Lookup tab. Double-click on the lookup table name that you want to specify in the function call and click OK.

Lookup Tab in the Expression Editor

For more information, see Verify Lookup Keys (Lookup Function).

Specify the LOOKUPVALUE Function in the Expression Editor

To use the Expression Editor to enter the LOOKUPVALUE function:

Click the LookupValue tab.
Double-click on the lookup table name.
Specify the term name or the character string that contains the lookup key value. To specify a term, double-click on the term in the Vocabulary column. To specify a character string as the lookup key value, enter the character string in the field at the top of the LookupValue tab. Enclose the string in quotation marks.
(Optional) Click Validate to check the syntax of the expression.
Click OK.

For more information, see Get Lookup Values (LookupValue Function).

LookupValue Tab in the Expression Editor

Punctuation for Data Values

Values for some data types might need to be enclosed in quotation marks, as shown in the following table. Date and Datetime values must be followed with d and dt, respectively.

Punctuation Needed for Data Values
Data Type	Punctuation Needed	Example
Character	Enclose character strings in either single or double quotation marks.	`='Gold Account'` `="Ineligible"` `="d'oscail"`
Date	Enter Date values by using the format DDMMMYYYY. Enclose each value in quotation marks followed by `d`.	`='01SEP2012'd` `>='31SEP2012'd`
Datetime	Enter Datetime values by using the format DDMMMYYYY:HH:MM:SS. Use 24-hour clock notation. Enclose each value in quotation marks followed by `dt`.	`='01SEP2012:15:00:00'dt` `<='31SEP2012:15:00:00'dt`
Boolean	Boolean values do not need to be enclosed in quotation marks. Enter only `True` or `False`.	`=True` `=False`

Operators for Use in Expressions

The following table lists the operators that you can use in an expression. Do not enter a space between the elements of the operators <=, >=, or ^=. See SAS Operators in Expressions in SAS Language Reference: Concepts for more information about the operators shown in the table.

Operators
Operator	Definition	Example
*	Multiply	`0.085 * sales`
/	Divide	`amount / 5`
+	Add	`num + 3`
–	Subtract	`sale - discount`
=	Equal to	`= maxTriesAllowed`
+value	Leading plus1	+60
–value	Leading minus1	–15
^=	Not equal to	`insufficientFunds ^= True`
>	Greater than	`daysLate > 5`
<	Less than	`num < 8`
>=	Greater than or equal to	`balance >= 1000`
<=	Less than or equal to	`balance <= 250`
IN (value-list)	Equal to an item in value-list	`in ('high','medium','low')`
NOT IN (value-list)	Not equal to an item in value-list	`not in (10,20,30)`
LIKE 'pattern-matching-expression' LIKE ('pattern-matching-expression','pattern-matching-expression')	If the term’s value matches pattern-matching-expression, the result is true.	`like 'HS%PP'` `like ('_976%','_223%')`
expression AND expression	If both expressions are true, the result is true.	`dateExpired >= '01AUG2012'd AND dateExpired <= '31AUG2012'd`
expression OR expression	If either expression is true, the result is true.	`dateEnrolled >= '01JAN2012' OR member = True`
1The application supports leading plus (+) and minus (-) operators in action expressions only.

Using the LIKE Operator

The LIKE operator determines whether the value of a term matches a pattern-matching expression. The syntax of an expression that uses the LIKE operator is as follows:

LIKE 'pattern-matching-expression'

LIKE ('pattern-matching-expression'<,'pattern-matching-expression'>)

If a term’s value matches the pattern that is specified by pattern-matching-expression, the expression evaluates to true (1). Otherwise, the expression evaluates to false (0).

There are three classes of pattern-matching characters.

Pattern-Matching Characters
Character	Description
underscore (_)	Matches any single character
percent sign (%)	Matches any sequence of zero or more characters Note: Be aware of the effect of trailing blanks. To match values, you might have to use the TRIM function to remove trailing blanks.
any other character	Matches that character

The LIKE expression is case sensitive. To search for mixed-case strings, use the UPCASE function to create an upper case version of the term that you want to search. You can use a temporary term to store the results of the UPCASE function. (See Step 8 of Create New Terms.) Use the LIKE operator to search the upper case version of the term.

For example, you can search the term part_Number for mixed-case strings that begin with HS and end with PP by using the two rules shown in the following display.

Decision table showing the temporary term “tempTerm” as both a condition term and an action term. The expression for the action term in rule 1 is “=upcase(part_Number)”. The expression for the condition term in rule 2 is “like(‘hs%pp’)”.

The following table shows examples of the matches that result if you search a term that could have these values: Smith, Smooth, Smothers, Smart, Smuggle.

Examples of LIKE Expressions
LIKE Expression Example	Matching Results
`like 'Sm%'`	`Smith, Smooth, Smothers, Smart, Smuggle`
`like '%th'`	`Smith, Smooth`
`like 'S__gg%'`	`Smuggle`
`like 'S_o'`	(no matches)
`like 'S_o%'`	`Smooth, Smothers`
`like 'S%th'`	`Smith, Smooth`

Using Functions in Expressions

SAS Decision Manager supports the following functions in rule expressions:

LOOKUP and LOOKUPVALUE functions. See Verify Lookup Keys (Lookup Function) and Get Lookup Values (LookupValue Function) for more information.
SAS DS2 functions. For information about these functions, see SAS DS2 Language Reference at http://support.sas.com/documentation/onlinedoc/brm/index.html.

Working with Missing Values

You can enter a missing value for a character string as a null string (=""), and you can use a period (=.) to designate missing numeric values.

Missing values have a value of false when you use them with logical operators such as AND or OR. For more information, see Missing Values in SAS Language Reference: Concepts.

You can also use the MISSING function to check for missing values. This function returns a 0 (false) or 1 (true). For more information, see SAS Functions and CALL Routines: Reference.

Terms and Operators Added by SAS Decision Manager

As you enter expressions into each cell, SAS Decision Manager displays the rule conditions and actions on the Rule Details tab. The operators and term names that are added by SAS Decision Manager are also displayed. Remember these rules when you are entering expressions:

If you do not specify an operator at the beginning of an expression, SAS Decision Manager adds an equal sign to the beginning of the expression. For example, if you enter 5+x for an expression, the expression resolves to =5+x.
When an AND or OR operator is followed immediately by another operator in a condition expression, SAS Decision Manager inserts the condition term between the AND or OR operator and the operator that follows it. For example, if you enter >5 and <10 for myterm, the expression resolves to myterm>5 and myterm<10. SAS Decision Manager inserts the term for top-level AND or OR operators in condition expressions only. It does not insert the term with nested AND or OR operators or in action expressions.

Examples of Expressions

The following table shows examples of expressions that you can specify.

Examples of Expressions
Expression As Entered Into the Decision Table For Term X	Resulting Expression	Valid as a Condition Expression	Valid as an Action Expression
`5`	`x=5`	Yes	Yes
`=5`	`x=5`	Yes	Yes
+10	x=x+10	No See Note 7.	Yes
`"mystring"`	`x="mystring"`	Yes	Yes
`=term1`	`x=term1`	Yes	Yes
`5 or >100`	`x=5 or x>100`	Yes	No See Note 1.
`^=5 and x<10`	`x^=5 and x<10`	Yes	No See Note 1.
`^=5 or >=(100/4)`	`x^=5 or x>=(100/4)`	Yes	No See Note 1.
`in (10,20,30)`	`x IN (10,20,30)`	Yes	No See Note 1.
`not in ('med','high')`	`x NOT IN ('MED','HIGH')`	Yes	No See Note 1.
`rate in ('med','high')`	`x = rate in ('med','high')`	Yes	Yes See Note 8.
`like ('M77__LL%','MA89_LL%')`	`x LIKE ('M77__LL%','MA89_LL%')`	Yes	No See Note 1.
`<'10JUN2012'd`	`x<'10JUN2012'd`	Yes	No See Note 1.
`>'10JUN2012:17:00:00'dt`	`x>'10JUN2012:17:00:00'dt`	Yes	No See Note 1.
`=ABS(-10)`	`x=ABS(-10)`	Yes	Yes
`=True`	`x=True`	Yes	Yes
`False`	`x=False`	Yes	Yes
`&myMacroVar`	`x=&myMacroVar`	Yes See Note 2.	Yes See Note 2.
`%EVAL(&myMacroVar)`	`x=%EVAL(&myMacroVar)`	Yes See Note 2.	Yes See Note 2.
`term1=5`	`x=term1=5`	Yes See Note 3.	Yes See Note 4.
`term1=3 or term2=5`	`x=term1=3 or term2=5`	Yes See Note 5.	Yes See Note 6.
`5 or (x>10 and <20)`	This expression is invalid as both a condition expression and as an action expression. SAS Decision Manager does not add column names after nested AND or OR operators.
`>"mystring"`	This expression is invalid as both a condition expression and as an action expression. SAS Decision Manager checks whether literal types are compatible with the specified operators. Character strings are not compatible with numeric operators.

Notes:

Action expressions must be assignment expressions only.
SAS Decision Manager validates macro functions and variables based only on whether the syntax is correct. It does not check to determine whether a macro function or variable will be accessible when the rule set is executed. Macro support in expressions is controlled by a configuration property in SAS Management Console. See Support macros in rule expressions in SAS Decision Manager: Administrator's Guide for more information.
This expression is valid. However, it should be avoided. As a condition statement, this expression checks to determine whether both x and term1 are equal to 5. The recommended way to enter this expression is =5 and term1=5.
As an action expression, this expression becomes a Boolean assignment statement. This expression determines whether term1 is equal to 5, and if so, assigns a value of 1 (true) to x. If not, it assigns a value of 0 (false) to x.
This expression is valid. However, it should be avoided. As a condition statement, this expression checks to determine whether both x and term1 are equal to 3 or whether term2 is equal to 5. The recommended way to enter this expression is (=5 or term1=3) or term2=5.
As an action expression, this expression becomes a Boolean assignment statement. This expression determines whether either term1 is equal to 3 or term2 is equal to 5, and if so, assigns a value of 1 (true) to x. If not, it assigns a value of 0 (false) to x.
Leading plus (+) and minus (-) operators are valid in action expressions only.
As an action expression, this expression becomes a Boolean assignment statement. The expression determines whether rate is equal to high or low, and if so, assigns a value of value of 1 (true) to x. If not, it assigns a value of 0 (false) to x.