FROM DEPT, EMP EMP1, EMP
SELECT DEPT.DEPT_NO, COUNT(*)
FROM DEPT, EMP EMP1, EMP EMP2
WHERE DEPT.DEPT_NO = EMP2.DEPT_NO AND
DEPT.DEPT_MNG = EMP1.EMP_NO AND
EMP1.DEPT_NO IS NULL
GROUP BY DEPT.DEPT_NO;
Введение в модель данных SQL
SELECT DEPT.DEPT_NO, COUNT(*)
FROM DEPT, EMP EMP1, EMP EMP2
WHERE DEPT.DEPT_NO = EMP2.DEPT_NO AND
DEPT.DEPT_MNG = EMP1.EMP_NO AND
EMP1.DEPT_NO IS NULL
GROUP BY DEPT.DEPT_NO;