--建立用戶
create user qjt identified by 1234ide
--權限
grant connect to qjt排序
grant resource to qjttable
--建表
create table userinfo
(id number primary key not null)test
--查詢有幾張表
select * from all_tables where owner='QJT'select
--僞列
select id,rowid,rownum from userinfo權限
--查詢天然排序的第三條記錄
select * from
(
select ename,rownum rn from emp
) temp
where rn=3分頁
--查詢教師表中薪水排名第五的教師信息
select * from
(
select rownum rn,ta.* from
(
select ename,sal,rownum rn from emp order by sal desc
)ta where rownum<6
)where rn>=5方法
--分頁
--方法一
select * from
(
select temp.*,rownum rn from
(
select emp.* from emp
order by sal desc
) temp
where rownum<=9
)
where rn>=5
--方法二
select * from
(
SELECT temp.*,ROWNUM rn FROM
(
SELECT * FROM emp e ORDER BY e.sal DESC
)temp
)temp2
WHERE TEMP2.rn BETWEEN 5 AND 9im
--受權
grant select on HAPPYY2165.STUDENT to scott數據
--解鎖用戶
alter user hr account unlock
--收回權限
revoke select on qjt from SCOTT
--經過角色控制
--自定義角色
CREATE role role_testy2165
--將查詢表的權限和角色綁定
grant SELECT ON Y2165."student" TO role_testy2165
--給用戶分配角色
GRANT role_testy2165 to SCOTT
--distinct查詢不重複的數據
select DISTINCT "stuname","stuage" from STUDENT;
--建立學生表的備份表
create table studentbak
as
select * from STUDENT
--刪除相同的列,保留id最大的
DELETE FROM student
WHERE "stuno" NOT IN(SELECT "MAX"("stuno") FROM student GROUP BY "stuname","stuage")
SELECT 1+1 FROM dual
SELECT '你'||'好' FROM dual
SELECT '運算結果'||'5' FROM dual
--交集
SELECT deptno FROM dept
INTERSECT
SELECT DISTINCT deptno FROM emp
--減集SELECT deptno FROM deptMINUS SELECT DISTINCT deptno FROM emp