CODE EXAMPLES

All examples are open source and ready to run locally.

COBOL (11 lines)

CREATE-EMP.cbl
OPEN I-O EMPLOYEE-FILE.
MOVE "E001" TO EMP-ID.
MOVE "John" TO EMP-FIRST-NAME.
MOVE "Smith" TO EMP-LAST-NAME.
MOVE "Engineering" TO EMP-DEPARTMENT.
MOVE 85000.00 TO EMP-SALARY.
MOVE "2020-01-15" TO EMP-HIRE-DATE.
WRITE EMPLOYEE-RECORD.
IF WS-SUCCESS
    DISPLAY "Employee created"
END-IF.
CLOSE EMPLOYEE-FILE.

⚙️ Explicit field-by-field assignment
⚙️ Manual file open/close
⚙️ Status checking required

SQL (2 lines)

create.sql
INSERT INTO employees (id, first_name, last_name, department, salary, hire_date)
VALUES ('E001', 'John', 'Smith', 'Engineering', 85000.00, '2020-01-15');

⚡ Single declarative statement
⚡ Automatic constraint validation
⚡ Database handles storage

MongoDB (7 lines)

create.js
db.employees.insertOne({
    _id: "E001",
    firstName: "John",
    lastName: "Smith",
    department: "Engineering",
    salary: 85000,
    hireDate: new Date("2020-01-15")
})

📦 JSON-like structure
📦 Flexible - can add extra fields
📦 Rich data types (Date objects)

COBOL - Sequential Scan (14 lines)

SEARCH-EMP.cbl
MOVE 0 TO WS-COUNT.
OPEN INPUT EMPLOYEE-FILE.
PERFORM UNTIL WS-EOF
    READ EMPLOYEE-FILE NEXT RECORD
        AT END
            SET WS-EOF TO TRUE
        NOT AT END
            IF EMP-DEPARTMENT = "Engineering"
                DISPLAY EMP-ID " - "
                    EMP-FIRST-NAME " " EMP-LAST-NAME
                ADD 1 TO WS-COUNT
            END-IF
    END-READ
END-PERFORM.
DISPLAY "Total found: " WS-COUNT.
CLOSE EMPLOYEE-FILE.

SQL - Declarative Query (3 lines)

search.sql
SELECT id, first_name, last_name, salary
FROM employees
WHERE department = 'Engineering'
ORDER BY salary DESC;

MongoDB - Query Document (2 lines)

search.js
db.employees.find({ department: "Engineering" })
    .sort({ salary: -1 })

COBOL - Manual Calculation (12 lines)

AGGREGATE-EMP.cbl
MOVE 0 TO WS-TOTAL, WS-COUNT.
OPEN INPUT EMPLOYEE-FILE.
PERFORM UNTIL WS-EOF
    READ EMPLOYEE-FILE NEXT RECORD
        AT END
            SET WS-EOF TO TRUE
        NOT AT END
            ADD EMP-SALARY TO WS-TOTAL
            ADD 1 TO WS-COUNT
    END-READ
END-PERFORM.
DIVIDE WS-TOTAL BY WS-COUNT GIVING WS-AVERAGE ROUNDED.
DISPLAY "Average salary: $" WS-AVERAGE.
CLOSE EMPLOYEE-FILE.

SQL - Built-in Functions (1 line)

aggregate.sql
SELECT AVG(salary) AS average_salary FROM employees;

MongoDB - Aggregation Pipeline (10 lines)

aggregate.js
db.employees.aggregate([
    {
        $group: {
            _id: null,
            avgSalary: { $avg: "$salary" },
            totalEmployees: { $sum: 1 },
            maxSalary: { $max: "$salary" },
            minSalary: { $min: "$salary" }
        }
    }
])

COBOL - Control Break Logic (~25 lines)

Requires sorted file first
* Requires file sorted by department
MOVE SPACES TO WS-CURRENT-DEPT.
PERFORM UNTIL WS-EOF
    READ EMPLOYEE-FILE NEXT RECORD
        AT END
            SET WS-EOF TO TRUE
            PERFORM PRINT-DEPT-STATS
        NOT AT END
            IF EMP-DEPARTMENT NOT = WS-CURRENT-DEPT
                IF WS-CURRENT-DEPT NOT = SPACES
                    PERFORM PRINT-DEPT-STATS
                END-IF
                MOVE EMP-DEPARTMENT TO WS-CURRENT-DEPT
                MOVE 0 TO WS-DEPT-COUNT, WS-DEPT-TOTAL
            END-IF
            ADD 1 TO WS-DEPT-COUNT
            ADD EMP-SALARY TO WS-DEPT-TOTAL
    END-READ
END-PERFORM.

PRINT-DEPT-STATS.
    DIVIDE WS-DEPT-TOTAL BY WS-DEPT-COUNT
        GIVING WS-DEPT-AVERAGE.
    DISPLAY WS-CURRENT-DEPT ": " WS-DEPT-COUNT
        " employees, avg $" WS-DEPT-AVERAGE.

SQL - Built-in GROUP BY (5 lines)

aggregate.sql
SELECT
    department,
    COUNT(*) as employee_count,
    AVG(salary) as avg_salary
FROM employees
GROUP BY department
ORDER BY avg_salary DESC;

MongoDB - $group Pipeline (10 lines)

aggregate.js
db.employees.aggregate([
    {
        $group: {
            _id: "$department",
            employeeCount: { $sum: 1 },
            avgSalary: { $avg: "$salary" }
        }
    },
    { $sort: { avgSalary: -1 } }
])