Editing COBOL Std 12 Common Defect Patterns Lessons from pgcobol

== 12. Common Defect Patterns (Lessons from pgcobol) ==

The following defects were observed in the pgcobol reference project and are documented here as anti-patterns to avoid:

{| class="wikitable" style="width:100%"
! ID !! Severity !! Description and Prevention
|-
| D-01 || High || Generate loop commented out in main program — generation mode silently does nothing. Never leave PERFORM stubs commented out without removing the WHEN branch that invokes them.
|-
| D-02 || Medium || Seed prime (2) never inserted — first-run leaves DB in invalid state for the sieve. Document and test first-run initialisation as a separate mandatory step.
|-
| D-03 || Medium || Connection alias mismatch (<code>primes</code> vs <code>primesdb</code>) causes runtime SQL error. Enforce a single alias constant in WORKING-STORAGE referenced everywhere.
|-
| D-04 || Medium || Hard-coded credentials in WORKING-STORAGE. Use environment variables (see [[#10. Configuration and Credentials|§10]]).
|-
| D-05 || Medium || COMMIT statement commented out after INSERT — relies on implicit auto-commit. Always include explicit COMMIT/ROLLBACK (see [[#6.4 Transaction Management|§6.4]]).
|-
| D-06 || Low || Two near-identical copybooks with different naming conventions (hyphens vs underscores). One copybook, one naming rule.
|-
| D-07 || Low || Report loop condition (<code>session-method-eof = 9</code>) never set on EOF; loop exits on error code 1 instead. Separate EOF (result=2) from error (result=1) per [[#7.1 Return-Code Standard|§7.1]].
|}

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