Diferença de hora entre logins

SELECT CASE
        WHEN COUNT(emp.logon_end_time) > 1 THEN 'Sim' ELSE 'Não'
      END AS "Teve Queda Hoje?", emp.EMPLOYEE_ID
FROM t_employee_logon emp
WHERE TRUNC(emp.logon_end_time) = TRUNC(SYSDATE)
GROUP BY emp.logon_end_time, emp.EMPLOYEE_ID
HAVING COUNT(emp.logon_end_time) > 1;

SELECT *
FROM t_employee_logon emp
WHERE employee_id = 'L84979'
AND TRUNC(emp.logon_end_time) = TRUNC(SYSDATE)
ORDER BY LOGON_START_DATE DESC, LOGON_START_TIME DESC;


SELECT ROUND((emp.logon_start_time - LAG(emp.logon_start_time) OVER (ORDER BY emp.logon_start_time)) * 1440) || ' minutos' AS "Minutos entre logins"
FROM t_employee_logon emp
WHERE employee_id = '98611'
AND TRUNC(emp.logon_end_time) = TRUNC(SYSDATE)
ORDER BY LOGON_START_DATE DESC, LOGON_START_TIME DESC
FETCH FIRST 1 ROW only;

SET SERVEROUTPUT ON
DECLARE
  v_aux VARCHAR(50);

  CURSOR c1 IS
    SELECT CASE
            WHEN COUNT(emp.logon_end_time) > 1 THEN 'Sim' ELSE 'Não'
          END AS "Teve Queda Hoje?", emp.EMPLOYEE_ID
    FROM t_employee_logon emp
    WHERE TRUNC(emp.logon_end_time) = TRUNC(SYSDATE)
    GROUP BY emp.logon_end_time, emp.EMPLOYEE_ID
    HAVING COUNT(emp.logon_end_time) > 1;

BEGIN
  FOR r1 IN c1 LOOP
    SELECT ROUND((emp.logon_start_time - LAG(emp.logon_start_time) OVER (ORDER BY emp.logon_start_time)) * 1440) || ' minutos' AS "Minutos entre logins"
    INTO v_aux
    FROM t_employee_logon emp
    WHERE employee_id = r1.employee_id
    AND TRUNC(emp.logon_end_time) = TRUNC(SYSDATE)
    ORDER BY LOGON_START_DATE DESC, LOGON_START_TIME DESC
    FETCH FIRST 1 ROW only;

    DBMS_OUTPUT.put_line(r1.employee_id || ': '  || v_aux);
  END LOOP;
END;