创建三个空表emp1,emp2,emp3,结构参考emp表
CREATE TABLE EMP1 AS SELECT * FROM EMP WHERE 1=2;
CREATE TABLE EMP2 AS SELECT * FROM EMP WHERE 1=2;
CREATE TABLE EMP3 AS SELECT * FROM EMP WHERE 1=2;
用一条INSERT语句将emp表中部门号为10的插入到emp1，20的插入到emp2,30的插入到emp3
INSERT ALL
WHEN DEPTNO=10 THEN
INTO EMP1
WHEN DEPTNO=20 THEN
INTO EMP2
WHEN DEPTNO=30 THEN
INTO EMP3
SELECT * FROM EMP;
创建一个表t35，x列为任意时间戳类型，插入当前时间，并查询
CREATE TABLE T35(X TIMESTAMP WITH LOCAL TIME ZONE);
INSERT INTO T35 VALUES(SYSDATE);
SELECT * FROM T35;
查询emp表所有员工信息，谁的薪金超过其部门的平均工资
SELECT ENAME,SAL,DEPTNO FROM EMP OUTER_TABLE
WHERE SAL>(SELECT AVG(SAL) FROM EMP INNER_TABLE WHERE INNER_TABLE.DEPTNO=OUTER_TABLE.DEPTNO);
查询emp中不是领导的几层员工信息
SELECT * FROM EMP OUTER_TABLE WHERE NOT EXISTS (SELECT 'X' FROM EMP INNER_TABLE WHERE INNER_TABLE.MGR = OUTER_TABLE.EMPNO);
查找dept表中没有任何员工的部门
SELECT DEPTNO,DNAME FROM DEPT WHERE NOT EXISTS(SELECT 'X' FROM EMP WHERE EMP.DEPTNO=DEPT.DEPTNO);
在hr用户授权scott可以查询employees，departments表的权限
GRANT SELECT ON DEPARTMENTS TO SCOTT;
GRANT SELECT ON EMPLOYEES TO SCOTT;
在scott用户创建同名employees,departments表并复制数据
CREATE TABLE EMPLOYEES AS SELECT * FROM HR.EMPLOYEES;
CREATE TABLE DEPARTMENTS AS SELECT * FROM HR.DEPARTMENTS;
在scott用户给employees表增加一列，部门名称
ALTER TABLE EMPLOYEES ADD(DNAME VARCHAR2(20));
在scott用户根据departments表的部门名称更新employees表的部门名称
UPDATE EMPLOYEES SET DNAME=(SELECT DEPARTMENT_NAME FROM DEPARTMENTS WHERE DEPARTMENTS.DEPARTMENT_ID=EMPLOYEES.DEPARTMENT_ID);
SELECT * FROM DEPARTMENTS;
SELECT * FROM EMPLOYEES;
在scott用户employees中删除在location_id是1700地区的员工信息
DELETE FROM EMPLOYEES WHERE DEPARTMENT_ID IN(SELECT DEPARTMENT_ID FROM DEPARTMENTS WHERE LOCATION_ID=1700);