oracle常用sql查询语句部分集合(图文)

Oracle查询语句

select * from scott.emp ;

1.--dense_rank()分析函数（查找每个部门工资最高前三名员工信息）

select * from (select deptno,ename,sal,dense_rank() over(partition by deptno order by sal desc) a from scott.emp) where a<=3 order by deptno asc,sal desc ;

结果：

--rank()分析函数(运行结果与上语句相同)

select * from (select deptno,ename,sal,rank() over(partition by deptno order by sal desc) a from scott.emp ) where a<=3 order by deptno asc,sal desc ;

结果：

--row_number()分析函数（运行结果与上相同）

select * from(select deptno,ename,sal,row_number() over(partition by deptno order by sal desc) a from scott.emp) where a<=3 order by deptno asc,sal desc ;

--rows unbounded preceding 分析函数（显示各部门的积累工资总和）

select deptno,sal,sum(sal) over(order by deptno asc rows unbounded preceding) 积累工资总和 from scott.emp ;

结果：

--rows 整数值 preceding(显示每最后4条记录的汇总值)

select deptno,sal,sum(sal) over(order by deptno rows 3 preceding) 每4汇总值 from scott.emp ;

结果：

--rows between 1 preceding and 1 following（统计3条记录的汇总值【当前记录居中】）

select deptno,ename,sal,sum(sal) over(order by deptno rows between 1 preceding and 1 following) 汇总值 from scott.emp ;

结果：

--ratio_to_report(显示员工工资及占该部门总工资的比例)

select deptno,sal,ratio_to_report(sal) over(partition by deptno) 比例 from scott.emp ;

结果：

--查看所有用户

select * from dba_users ;

select count(*) from dba_users ;

select * from all_users ;

select * from user_users ;

select * from dba_roles ;

--查看用户系统权限

select * from dba_sys_privs ;

select * from user_users ;

--查看用户对象或角色权限

select * from dba_tab_privs ;

select * from all_tab_privs ;

select * from user_tab_privs ;

--查看用户或角色所拥有的角色

select * from dba_role_privs ;

select * from user_role_privs ;

-- rownum:查询10至12信息

select * from scott.emp a where rownum<=3 and a.empno not in(select b.empno from scott.emp b where rownum<=9);

结果：

--not exists；查询emp表在dept表中没有的数据

select * from scott.emp a where not exists(select * from scott.dept b where a.empno=b.deptno) ;

结果：

--rowid;查询重复数据信息

select * from scott.emp a where a.rowid>(select min(x.rowid) from scott.emp x where x.empno=a.empno);

--根据rowid来分页(一万条数据，查询10000至9980时间大概在0.03秒左右)

select * from scott.emp where rowid in(select rid from(select rownum rn,rid from(select rowid rid,empno from scott.emp order by empno desc) where rownum<10)where rn>=1)order by empno desc ;

结果：

--根据分析函数分页(一万条数据，查询10000至9980时间大概在1.01秒左右)

select * from(select a.*,row_number() over(order by empno desc) rk from scott.emp a ) where rk<10 and rk>=1;

结果：

--rownum分页(一万条数据，查询10000至9980时间大概在0.01秒左右)

select * from(select t.*,rownum rn from(select * from scott.emp order by empno desc)t where rownum<10) where rn>=1;

select * from(select a.*,rownum rn from (select * from scott.emp) a where rownum<=10) where rn>=5 ;

--left outer join:左连接

select a.*,b.* from scott.emp a left outer join scott.dept b on a.deptno=b.deptno ;

--right outer join:右连接

select a.*,b.* from scott.emp a right outer join scott.dept b on a.deptno=b.deptno ;

--inner join

select a.*,b.* from scott.emp a inner  join scott.dept b on a.deptno=b.deptno ;

--full join

select a.*,b.* from scott.emp a full join scott.dept b on a.deptno=b.deptno ;

select a.*,b.* from scott.emp a,scott.dept b where a.deptno(+)=b.deptno ;

select distinct ename,sal from scott.emp a group by sal having ;

select * from scott.dept ;

select * from scott.emp ;

--case when then end (交叉报表)

select ename,sal,case deptno when 10 then '会计部' when 20 then '研究部' when 30 then '销售部' else '其他部门' end 部门 from scott.emp ;

结果：

select ename,sal,case when sal>0 and sal<1500 then '一级工资' when sal>=1500 and sal<3000 then '二级工资' when sal>=3000 and sal<4500 then '三级工资' else '四级工资' end 工资等级 from scott.emp order by sal desc ;

结果：

--交叉报表是使用分组函数与case结构一起实现

select 姓名,sum(case 课程 when '数学' then 分数 end)数学,sum(case 课程 when '历史' then 分数 end)历史 from 学生 group by 姓名 ;

--decode 函数

select 姓名,sum(decode(课程,'数学',分数,null))数学,sum(decode(课程,'语文',分数,null))语文,sum(decode(课程,'历史','分数',null))历史 from 学生 group by 姓名 ;

--level。。。。connect by(层次查询)

select level,emp.* from scott.emp connect by prior empno = mgr order by level ;

结果：

--sys_connect_by_path函数

select ename,sys_connect_by_path(ename,'/') from scott.emp start with mgr is null connect by prior empno=mgr ;

结果：

--start with connect by prior 语法

select lpad(ename,3*(level),'')姓名,lpad(ename,3*(level),'')姓名 from scott.emp where job<>'CLERK' start with mgr is null connect by prior mgr = empno ;

--level与prior关键字

select level,emp.* from scott.emp start with ename='SCOTT' connect by prior empno=mgr;

select level,emp.* from scott.emp start with ename='SCOTT' connect by empno = prior mgr ;

结果：