FROM PRO) AS PRO1
SELECT COUNT (*), PRO_EDATE, AVG_SAL
FROM (SELECT PRO_EDATE, AVG (EMP_SAL)
FROM (SELECT PRO_SDATE + PRO_DURAT, PRO_NO
FROM PRO) AS PRO1 (PRO_EDATE, PRO_NO), EMP
WHERE PRO1.PRO_NO = EMP.PRO_NO
GROUP BY PRO1.PRO_NO ) AS PRO_AVG_SAL (PRO_EDATE, AVG_SAL)
GROUP BY PRO_EDATE, AVG_SAL;
