【正文】
OM emp3列出部門名稱和這些部門的雇員,同時列出那些沒有雇員的部門(重要)SELECT dname , enameFROM dept LEFT JOIN emp ON = ORDER BY dname列出那些沒有雇員的部門 SELECT dnameFROM emp RIGHT JOIN dept ON = WHERE IS NULL列出每個部門的信息以及該部門中雇員的數量(重要)SELECT dept.*, COUNT() 人數FROM dept LEFT JOIN ON = GROUP BY , ORDER BY 4列出薪金比SMITH多的所有雇員SELECT , FROM empWHERE sal ( SELECT sal FROM emp WHERE ename = 39。smith39。 ) 4列出所有雇員的姓名及其直接上級的姓名SELECT 雇員 , 直接上級FROM A LEFT JOIN B ON = ORDER BY 4列出入職日期早于其直接上級的所有雇員SELECT ename 雇員 , hiredate 雇員入職日期FROM emp eWHERE hiredate ( SELECT hiredate FROM emp WHERE empno = )4列出所有辦事員(CLERK)的姓名及其部門名稱SELECT ename , dname , jobFROM emp e JOIN dept d ON = WHERE job = 39。CLERK39。4列出從事SALES(銷售)工作的雇員的姓名,假定不知道銷售部的部門編號SELECT enameFROM empWHERE deptno = ( SELECT deptno FROM dept WHERE dname = 39。sales39。 )4列出與SCOTT從事相同工作的所有雇員SELECT ename , jobFROM empWHERE job = ( SELECT job FROM emp WHERE ename = 39。SCOTT39。 ) 4列出某些雇員的姓名和薪金,條件是他們的薪金等于部門30中任何一個雇員的薪金SELECT ename , sal , deptnoFROM empWHERE sal IN ( SELECT sal FROM emp WHERE deptno = 30 )4列出某些雇員的姓名和薪金,條件是他們的薪金高于部門30中所有雇員的薪金SELECT ename , sal , deptnoFROM empWHERE sal ( SELECT MAX(sal) FROM emp WHERE deptno = 30 ) 4列出從事同一種工作但屬于不同部門的雇員的不同組合SELECT 雇員A , 雇員B , 雇員A工作 , 雇員B工作 , 雇員A部門 , 雇員B部門FROM emp a JOIN emp b ON = WHERE != AND = ORDER BY 50、列出所有雇員的雇員名稱、部門名稱和薪金(包括沒有雇員的部門)SELECT , , FROM RIGHT JOIN ON =