【sql查询与优化】3.操作多个表

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SQL> select * from emp;

SQL> select * from dept t;

SQL>  select empno as 编码, ename as 名称, nvl(mgr,deptno) as 上级编码
          from emp
          union all
          select deptno as 编码,dname as 名称,NULL as 上级编码
          from dept;

SQL> select '' as cl from dual;

SQL> select empno,ename from emp where empno = 1116 or ename = '林建国';

SQL> select empno,ename from emp where empno = 1116
     union all
     select empno,ename from emp where ename = '林建国';

SQL> select empno,ename from emp where empno = 1116
     union
     select empno,ename from emp where ename = '林建国';

SQL> select distinct deptno
     from (select deptno from emp where mgr = 3320
           union all
           select deptno from emp where job = '后勤')
     order by 1;

SQL> select empno,deptno from emp where mgr = 3320
     union
     select empno,deptno from emp where job = '后勤';

SQL> select deptno
          from
          (select ROWID,deptno from emp where mgr = 3320
               union
           select ROWID,deptno from emp where job = '后勤')
          order by 1;

SQL> select e.empno,e.ename,d.dname
     from emp e
     inner join dept d on (e.mgr = d.deptno)
     where e.deptno = 30;

select e.empno,e.ename,d.dname
     from emp e,dept d
     where e.mgr = d.deptno
     and e.deptno = 30;

SQL> create table emp2 as
  2  select ename,job,sal,comm from emp where job = '销售';

SQL> select empno,ename,job,sal,deptno
     from emp
     where (ename,job,sal) in (select ename,job,sal from emp2);

SQL> select empno,ename,job,sal,deptno
          from emp a
          where exists (select null
                      from emp2 b
                    where b.ename = a.ename
                    and b.job = a.job
                    and b.sal = a.sal);

SQL> select a.empno,a.ename,a.job,a.sal,a.deptno
     from emp a
     inner join emp2 b on (b.ename = a.ename and b.job = a.job and b.sal = a.sal);

/*左表*/
create table L as
select 'left_1' as str,'1' as v from dual union all
select 'left_2','2' as v from dual union all
select 'left_3','3' as v from dual union all
select 'left_4','4' as v from dual;


/*右表*/
create table R as
select 'right_3' as str,'3' as v,1 as status from dual union all
select 'right_4' as str,'4' as v,0 as status from dual union all
select 'right_5' as str,'5' as v,0 as status from dual union all
select 'right_6' as str,'6' as v,0 as status from dual;

SQL> select * from L;

SQL> select * from R;

SQL> select L.str as left_str,R.str as right_str
     from L
     inner join R on L.v = R.v
     order by 1,2;

SQL> select L.str as left_str,R.str as right_str
     from L,R
     where L.v = R.v
     order by 1,2;

SQL> select L.str as left_str,R.str as right_str
     from L
     left join R on L.v = R.v
     order by 1,2;

SQL> select L.str as left_str,R.str as right_str
     from L,R
     where L.v = R.v(+)
     order by 1,2;

SQL> select L.str as left_str,R.str as right_str
     from L
     right join R on L.v = R.v
     order by 1,2;

SQL> select L.str as left_str,R.str as right_str
     from L,R
     where L.v(+) = R.v
     order by 1,2;

SQL> select L.str as left_str,R.str as right_str
     from L
     full join R on L.v = R.v
     order by 1,2;

create table emp3 as
select 7839 as empno,'tom' as ename,1 as mgr from dual union all
select 7566 as empno,'jean' as ename,7839 as mgr from dual union all
select 7788 as empno,'jack' as ename,7566 as mgr from dual union all
select 7902 as empno,'allen' as ename,7788 as mgr from dual union all
select 7369 as empno,'adams' as ename,7902 as mgr from dual union all
select 7698 as empno,'jeckson' as ename,7839 as mgr from dual;

SQL> select * from emp3;

SQL> select 员工.empno as 职工编码,
          员工.ename as 职工姓名,
          员工.mgr as 员工表_主管编码,
          主管.empno as 主管表_主管编码,
          主管.ename as 主管姓名
     from emp3 员工
     left join emp3 主管 on (员工.mgr = 主管.empno)
     order by 1;

SQL> select * from dept where deptno not in (select emp.mgr from emp where emp.m
gr is not null);

SQL> select L.str as left_str,R.str as right_str,R.status
     from L
     left join R on L.v = R.v
     order by 1,2;

select L.str as left_str,R.str as right_str,R.status
     from L
     left join R on L.v = R.v
     where R.status = 1
     order by 1,2;

select L.str as left_str,R.str as right_str,R.status
     from L
     where L.v = R.v(+)
     and R.status = 1
     order by 1,2;

select L.str as left_str,R.str as right_str,R.status
     from L
     left join R on (L.v = R.v and r.status = 1)
     order by 1,2;

select L.str as left_str,R.str as right_str,R.status
     from L,R
     where L.v = R.v(+)
     and status(+) = 1
     order by 1,2;

select L.str as left_str,R.str as right_str,R.status
     from L
     left join (select * from R where R.status = 1)R on (L.v = R.v)
     order by 1,2;

create or replace view v as
     select * from emp where deptno != 20
     union all
     select * from emp where ename = '李磊磊';

SQL> select rownum,empno,ename from v where ename = '李磊磊';

SQL> select rownum,empno,ename from emp where ename = '李磊磊';

SQL> select v.empno,v.ename,b.empno,b.ename
     from v
     full join emp b on (b.empno = v.empno)
     where (v.empno is null or b.empno is null);

SQL> select v.empno,v.ename,v.cnt,emp.empno,emp.ename,emp.cnt
     from (select empno,ename,COUNT(*) as cnt from v group by empno,ename) v
     full join (select empno,ename,COUNT(*) as cnt from emp group by empno,ename) emp
     on (emp.empno = v.empno and emp.cnt = v.cnt)
     where (v.empno is null or emp.empno is null);

create table emp_bonus (empno INT,received DATE,type INT);
insert into emp_bonus values( 1111,date '2016-5-17',1);
insert into emp_bonus values( 1112,date '2016-2-15',2);
insert into emp_bonus values( 1115,date '2016-2-15',3);

SQL> select * from emp_bonus;

SQL> select e.empno,e.ename,e.sal 
            from emp e 
            where e.deptno = 30;

SQL> select e.empno,
            e.ename,
            e.sal,
            (e.sal * case
                 when eb.type = 1 then 0.1
                 when eb.type = 2 then 0.2
                 when eb.type = 3 then 0.3
             end) as bonus
         from emp e
        inner join emp_bonus eb on (e.empno = eb.empno)
        where e.deptno = 30
        order by 1,2;

SQL> select e.deptno,
                 SUM(e.sal) as total_sal,
                 SUM(e.sal * case
                      when eb.type = 1 then 0.1
                      when eb.type = 2 then 0.2
                      when eb.type = 3 then 0.3
                  end) as total_bonus
              from emp e
             inner join emp_bonus eb on (e.empno = eb.empno)
             where e.deptno = 30
             group by e.deptno;

SQL> select e.deptno,
            SUM(e.sal) as total_sal,
            SUM(e.sal * eb2.rate) as total_bonus
        from emp e
        left join (select eb.empno,
                            SUM(case
                                 when eb.type = 1 then 0.1
                                 when eb.type = 2 then 0.2
                                 when eb.type = 3 then 0.3
                             end) as rate
                      from emp_bonus eb
                      group by eb.empno) eb2 on eb2.empno = e.empno
              group by e.deptno
              order by 1;

【sql查询与优化】3.操作多个表

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原文地址：http://blog.csdn.net/acmman/article/details/51062195