oracle 11g

1. 使用sqlplus进入oracle登陆窗口，输入用户名和密码，或使用cmd进入dos窗口使用 sqlplus scott/tiger as sysdba直接进入数据库
2. 使用alter user scott account unlock解锁用户
3. dual表：数学表达式
4. 获取系统当前时间：select sysdate from dual;
5. 别名：select ename,sal*12 annual_sal from emp;
6. 字符串相加：select ename||sal from emp;  (||相加)字符串使用单引号，使用两个单引号来转义一个单引号
7. 转义字符默认为 ，select ename from where ename like '%\%%';选择名字中含有%的记录，也可使用select ename from emp where ename like '%#%%' escape '#'自定义转义字符;
8. lower(upper)函数：select lower(ename) from emp;
9. substr函数，从第一个字符开始取三个字符：select substr(ename,1,3) from emp;
10. chr函数将ascii码的值转化成字符： select char(65) from dual; ascii则相反：select ascii('A') from dual;
11. to_char函数，格式化成指定格式的字符串：select to_char(sal,'$99,999.9999') from emp;使用L代替$则为本地货币即(人民币)：￥
12. to_date函数：select ename,to_char(hiredate,'YYYY-MM-DD HH24:MI:SS') from emp where hiredate > to_date('1981-02-20 12:00:00','YYYY-MM-DD HH24:MI:SS');
13. to_number函数：select sal from emp where sal > to_number('$1,547.99','$99,999.99');
14. nvl函数：select ename,sal*12+comm from emp;    --->  select ename,sal*12+nvl(comm,0) from emp;
15. max,min,avg,sum,count函数:select count(distinct deptno) from emp;
16. group by: select deptno,job,max(sal) from emp group by deptno,job;
17. select enam from emp where sal=(select max(sal) from emp);
18. select ename,deptno,max(sal) from emp group by ename,deptno;
19. select avg(sal),deptno from emp group by deptno having avg(sal) > 2000;
20. tip:敲入ed，复制命令到afiedt.buf,修改后关闭保存返回到sqlplus命令行输入/执行修改后的命令
21. 子查询join .. on ..：select ename,sal from emp
    join (select deptno,max(sal) max_sal from emp group by deptno) em
    on (emp.sal=em.max_sal and emp.deptno = em.deptno)
22. 自身表连接：1.select emp.ename,t.ename from emp join (select ename,empno from emp) t on emp.mgr = t.empno
    　　           2.select e1.ename,e2.ename from emp e1,emp e2 where e1.mgr=e2.empno
23. select ename,dname from emp join dept on (emp.deptno = dept.deptno) <--->select ename,dname from emp join dept using(deptno)
24. dba登陆：conn sys/密码 as sysdba; 授权：grant create table,create view to scott;
25. create view v$_dept_avg_sal_grade as select deptno,grade,avg_sal from (select deptno,avg(sal) avg_sal from emp group by deptno) t join salgrade s
        on (t.avg_sal between losal and hisal);
26. 备份数据库,使用dba帐号登陆：使用exp导出，在此过程中要输入要备份的用户
27. 创建新用户并授予权限：create user 用户名 identified by 密码 default tablespace users quota 10M on users;
    　　                        grant create session,create table,create view to 用户
28. 导入数据：imp  事务回滚：rollback
29. 创建一个新表并把指定表的数据copy到新表中：create table emp2 as select * from emp;   (insert into emp2 select * from emp)
30. rownum: select empno,ename from emp where rownum <= 5;
31. 分页查询：select ename,sal,r from (select ename,sal,rownow r from (select ename,sal from emp order by sal)) where r between 6 and 10;
32. transaction管理：commit，DDL语句，正常退出事务自动提交，rollback，非正常退出事务自动回滚。
33. 创建表：
      create table stu(id number(6),name varchar2(20),sex number(1),sdate date,grade number default 1,email varchar2(50));
     约束条件（字段）：create table stu(id nunber(6) unique,name varchar2(20) not null,.....);
    约束条件（表）：create table stu (id.....  email varchar2(50) constraint stu_name_email_un unique(name,email));
    create table class(id nubmer(6) primary key, name varchar2(20) not null);
34. 约束：not null,unique,primary key,foreign key
35. 修改表结构： alter table stu add(addr varchar2(100));  alert table stu drop(addr);
36. alert table stu modify(addr varchar2(150));
37. alert table stu drop constraint xxx;
38. desc user_tables;  查看当前用户下的所有的表：select table_name from user_tables; 查看视图：select view_name from user_views;
39. 数据字典：desc dictionary;
40. 创建索引：create index idx_stu_email on stu(email);
41. sequence:create sequence seq;    select seq.nextval from dual;  insert into article values(seq.nextval,'a','b');
42. PL/SQL:    begin
    　　          dbms_output.put_line('HelloWorld');
                    end;
                    /
                  在执行以上命令之前(打开显示功能）:set serveroutput on;
43. 变量声明：declare v_name varchar2(20); begin v_name='myname'; dbms_output.put_line(v_name);  end; /
44. --注释一行
45. 数据类型：binary_integer(计数),number,long(最大2G),boolean(不能使用dbms_output.put_line来打印boolean类型的数据),date,char,varchar2
46. 使用%type来指定变量类型：declare
                                         v_empno0 number(4);
                                         v_empno1 emp.empno%type;
                                         v_empno2 empno1%type;                                   
47. ddl语句：begin 
    　　         execute immediate 'create table T (name varchar2(20) default  ''aaa'')'
                  end;
                  /
48. if... elsif...else  end if:declare
     v_sal emp.sal%type;
    begin
     select sal into v_sal from emp
          where empno = 7369;
     if(v_sal <1200) then
         dbms_output.put_line('low');
     elsif(v_sal<2000) then
          dbms_output.put_line('middle');
     else
         dbms_output.put_line('high');
     end if;
    end;
49. 循环：declare
     i binary_integer := 1;
    begin
     loop
       dbms_output.put_line(i);
      i := i+1;
      exit when (i>=11);
    end loop;
    end;
    
     declare
      j binary_integer := 1;
     begin
      while j<11 loop
       dbms_output.put_line(j);
       j := j + 1;
      end loop;
     end;
    
     begin
      for k in 1..10 loop
       dbms_output.put_line(k);
      end loop;
      for k in reverse 1..10 loop
       dbms_output.put_line(k);
      end loop;
     end;
50. 创建序列： create sequence seq_errorlog_id start with 1 increment by 1;
51. 游标（cursor）：
     declare
      cursor c is
              select * from emp;
      v_emp c%rowtype;
     begin
      open c;
     fetch c into v_emp;
     dbms_output.put_line(v_emp.ename);
     close c;
     end;
    
    
     declare
      cursor c is
              select * from emp;
      v_emp c%rowtype;
     begin
      open c;
       loop
        fetch c into v_emp;
        exit when (c%notfound);
        dbms_output.put_line(v_emp.ename);
       end loop;
      close c;
     end;
    
    
    declare
     cursor c is
             select * from emp;
     v_emp c%rowtype;
    begin
     open c;
      fetch c into v_emp;
      while (c%found) loop
       dbms_output.put_line(v_emp.ename);
       fetch c into v_emp;
      end loop;
     close c;
    end;
    
    declare
     cursor c is
      select * from emp;
     begin
      for v_emp in c loop
      dbms_output.put_line(v_emp.ename);
     end loop;
    end;
    
    
52. procedure(存储过程):创建-->
    create or replace procedure p
     is
       cursor c is
         select * from emp2 for update;
     begin
      for v_emp in c loop
         if(v_emp.deptno = 10) then
           update emp2 set sal = sal + 10 where current of c;
         elsif(v_emp.deptno =20) then
           update emp2 set sal = sal + 20 where current of c;
         else
           update emp2 set sal = sal + 50 where current of c;
         end if;
       end loop;
       commit;
     end;
    调用-->:  exec p; 或者 begin  p; end;
53. 带参数的存储过程：创建-->
    create or replace procedure p
      (v_a in number, v_b number, v_ret out number,v_temp in out number)--in传入参数,out返回值,in out传入和返回参数,默认为in
     is
      begin
         if(v_a > v_b) then
          v_ret := v_b;
         else
          v_ret := v_b;
         end if;
         v_temp := v_temp + 1;
     end;
    调用-->
     declare
      v_a number := 3;
      v_b number := 4;
      v_ret number;
      v_temp number := 5;
     begin
      p(v_a,v_b,v_ret,v_temp);
      dbms_output.put_line(v_ret);
      dbms_output.put_line(v_temp);
     end;
54. 函数： 创建-->
     create or replace function sal_tax
      (v_sal number)
     return number
     is
     begin
      if(v_sal <2000) then
      return 0.10;
      elsif (v_sal <2750) then
       return 0.15;
     else
      return 0.20;
     end if;
     end;
    调用-->与其他内置函数一样 select lower(ename),sal_tax(sal) from emp;
55. trigger(触发器):
    创建一张log表-->
    create table emp2_log(
    uname varchar2(20),
    action varchar2(10),
    atime date
    )
    创建触发器-->(级联更新—— update emp2 set deptno = :NEW.deptno where deptno = :OLD.deptno;)
      create or replace trigger trig
       after insert or delete or update on emp2 for each row
      begin
        if inserting then
           insert into emp2_log values( USER, 'insert',sysdate);
        elsif updating then
           insert into emp2_log values (USER,'update',sysdate);
        elsif deleting then
           insert into emp2_log values (USER,'detele',sysdate);
        end if;
     end;