begin
    for i in 1..10 loop
        insert into t1 values(i);
    end loop;
    commit;
end;（功能结束就加分号，块结束）

create or replace procedure p1
    as
        begin
            for i in 1..10 loop
                insert into t1 values(i);
            end loop;
            commit;
        end;

    select a.id,b.id from t1 a,t1 b
    where a.id+5=b.id;
    或者where a.id+(select count(*) from t1)/2=b.id;
    where a.id+round((select count(*) from t1)/2)=b.id; //round 四舍五入
    不显示12的话，用外部语句
    where a.id+round((select count(*) from t1)/2)=b.id(+); //报错
    where a.id=b.id(+)-round((select count(*) from t1)/2);
    and a.id<=round((select count(*) from t1)/2);

        查询lastname，
        条件老百姓，不要领导
        select last_name from employees
        where employee_id not in (select nvl(manager_id,0)  from employees)
        select last_name from employees e
        where not exists
            (select employee_id from employees
            where e.employee_id = manager_id)

        select empno,ename from emp where ename=upper(&xm);
        define gh=7839; //undefine 取消定义
        select empno,ename from emp where ename=&gh;

        select empno,ename,&c3 from emp order by &c3;
        select empno,ename,&&c3 from emp order by &c3;

grant ...限制
select department_id from departments order by 1;