Easytrieve CASE Statement

Statement Format

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CASE field-name
 
  WHEN compare-literal-1 [THRU range-literal-1]
    statement-1
 
  WHEN compare-literal-n [THRU range-literal-n]
    statement-n
 
  [OTHERWISE
    statement-default]
 
END-CASE

Broadcom Vacation Example

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FILE EMPLOYEE
  EMPYRS   5   2   N
 
JOB INPUT EMPLOYEE
  CASE EMPYRS
    WHEN 0 THRU 4
      DISPLAY 'ONE WEEK VACATION'
    WHEN 5 THRU 10
      DISPLAY 'TWO WEEKS VACATION'
    OTHERWISE
      DISPLAY 'THREE WEEKS VACATION'
  END-CASE

EMPYRS two-digit numeric years of service: zero through four gets one week message, five through ten two weeks, all higher values OTHERWISE three weeks. Boundary four and five belong to different branches—test both.

WHEN Clause Semantics

OTHERWISE Default Branch

OTHERWISE executes when no WHEN matched—catch-all for unexpected codes. Omit OTHERWISE when fall-through to code after END-CASE is intentional silent ignore. Data quality jobs often OTHERWISE DISPLAY unknown code and increment error counter. Document whether unknown status should fail job or continue.

CASE Versus IF ELSE-IF Chain

IF DEPT EQ 10 ... ELSE-IF DEPT EQ 20 equivalent to CASE DEPT WHEN 10 ... WHEN 20. CASE wins readability when many values of same field. IF wins when conditions mix unrelated fields— IF DEPT EQ 10 AND STATUS EQ ACTIVE. Do not force CASE when no single driving field exists.

Nesting Rules

Broadcom allows CASE nested in CASE, CASE in IF, IF in WHEN body. Deep nesting hurts readability—extract inner CASE to PROC when beyond two levels. Each nested CASE needs its own END-CASE—match terminators carefully in code review.

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CASE REGION
  WHEN 'E'
    CASE STATUS
      WHEN 'A'
        PERFORM ACTIVE-EAST
      WHEN 'I'
        PERFORM INACTIVE-EAST
      END-CASE
  WHEN 'W'
    PERFORM WEST-LOGIC
  END-CASE

Overlap and Order

First matching WHEN executes; overlapping ranges cause earlier WHEN to shadow later—order WHEN from most specific to general or ensure ranges disjoint. WHEN 0 THRU 10 before WHEN 5 THRU 7 means five through seven never reach second WHEN if first matches—actually first includes five through seven so second is dead code. Static analysis in review catches dead WHEN branches.

Statements Inside WHEN

WHEN body may contain multiple statements—DISPLAY, assignment, PERFORM, nested CASE. No requirement for single statement. Indent for maintenance. Large bodies suggest PERFORM PROC per branch keeping CASE skeleton visible.

Testing CASE Logic

1. Test value below lowest range, each boundary, mid-range, above highest.
2. Test OTHERWISE with value outside all WHEN ranges.
3. Test no OTHERWISE no match falls through after END-CASE.
4. Verify numeric versus character CASE field type matches literals.
5. Regression test after adding new WHEN in middle of list.

Common CASE Mistakes

• Missing END-CASE.
• Overlapping WHEN ranges with wrong order.
• Using CASE when conditions are not on one field.
• Character literal without quotes on alphabetic field.
• Assuming last WHEN wins—first match wins.
• Deep nest without PROC extraction.

Explain It Like I'm Five

CASE is a vending machine with labeled buttons for one knob position. The knob is your field value. When knob points at five, the machine looks for the button labeled five or the range that includes five and drops that snack. OTHERWISE is the default snack if no label fits. END-CASE is closing the machine door when you are done choosing.

Exercises

1. Write CASE on STATUS with three WHEN codes and OTHERWISE.
2. Convert four-line ELSE-IF on REGION to CASE form.
3. Identify dead WHEN in overlapping range example.
4. Add nested CASE for STATUS inside REGION WHEN E.
5. List test values for EMPYRS vacation example.