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  • Oracle基础

    --创建用户
    create user qjt identified by 1234
    
    --权限
    grant connect to qjt
    
    grant resource to qjt
    
    --建表
    create table userinfo
    (id number primary key not null)
    
    --查询有几张表
    select * from all_tables where owner='QJT'
    
    --伪列
    select id,rowid,rownum from userinfo
    
    --查询自然排序的第三条记录
    select * from
    (
    select ename,rownum rn from emp
    ) temp
    where rn=3
    
    --查询教师表中薪水排名第五的教师信息
    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
    
    --分页
    --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 9
    
    --授权
    grant select on HAPPYY2165.STUDENT to scott
    
    --解锁用户
    alter user hr account unlock
    
    --收回权限
    revoke select on qjt from SCOTT
    
    --通过角色控制
    --自定义角色
    CREATE role role_testy2165
    
    --将查询表的权限和角色绑定
    grant SELECT ON Y2165."student" TO role_testy2165
    
    --给用户分配角色
    GRANT role_testy2165 to SCOTT
    
    
    --distinct查询不重复的数据
    select DISTINCT "stuname","stuage" from STUDENT;
    
    --创建学生表的备份表
    create table studentbak
    as
    select * from STUDENT
    
    --删除相同的列,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 ''||'' FROM dual
    
    SELECT '运算结果'||'5' FROM dual
    
    --交集
    SELECT deptno FROM dept
    INTERSECT 
    SELECT DISTINCT deptno FROM emp
    
    --减集
    SELECT deptno FROM dept
    MINUS 
    SELECT DISTINCT deptno FROM emp
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  • 原文地址:https://www.cnblogs.com/hhda/p/7542445.html
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