转 oracle数据库常用语句

1． 数据类型：字符类型：char(标准通用拉丁字符),nchar(汉字等其他字符),varchar2(长度可变字符),nvarchar2,long;
数字类型：number(通用),integer,float
日期和时间：date,timestamps(分秒，时区)
行：rowid(逻辑地址),urowid（逻辑地址，内存地址）;
二进制:raw(size)(原始二进制数据),long raw,blob(二进制大型对象;最大4G字节),clob(字符大型对象),nclob,bfile;

2.oracle WEB管理页面：localhost:5560/isqlplus; localhost:5500/em
3.net设置远程测试：tnsping datebasename；远程连接:sqlplus name/password@datebasename;

4.创建表空间：create tablespace test
datafile 'test.dbf' size 10m autoextend on next 2m
maxsize unlimited
logging
permanent
extent management local autoallocate
blocksize 8k
segment space management manuaL;//段空间

5．创建用户并连接： create user "TEST" identified by "TEST"
default tablespace TEST
temporary tablespace TEMP
quota unlimited on TEST
quota unlimited on TEMP
grant "connect" to test//分配基本权限。
conn test/test;

6．重设用户密码：scott/tiger为默认用户，alter user scott identified by tiger;
                 解锁：alter user scott account unlock;

7.sql脚本的执行：@路径/filename.sql;

8.创建表：create table t1(c1 type 约束,c2 type 约束（not null,unique,check,primary key））

9.查询：select distinct c1 from t1 where 条件 group by c1 having by 子条件order by c1;

10．连接字符串：select c1 (as可省) 列1 ||c2 from t1;

11.单行函数：select lower(c1) from t1；upper全大写，initcap第一个字母大写，length；

12．Select Sysdate from dual(系统默认的空表)显示系统时间,months_between(date,date);

13.round(数据,5位数),to_date(1997-10-11,’yyyy-mm-dd’)，to_char()函数使用要转换。

14.nvl(c1,0)把字段为空的值换为0，nvl2(c1,1,0)不空的为1，空的值为0；

15.操作符：比较：=，<>,>=,<=,>,<；逻辑：and,or,not
   其他：in/not in,between..and..,is null/is not null,like，exists/not exists；
Eg:select count(distinct c1) as 种类 from t1 where c1 like ‘%l%’(模糊查询如m_n)(c1 between 10 and 100) group by c1 order by c1 desc，c2 desc（不写就默认asc）

16．聚合函数：count(*)返回所有行的记录数,min(c1),max(c1),sum(c1),avg(c1);
Eg:select c1,count(*) from t1 group by c1 having by count(*)>1;(having不能用变量申明);等价于select c1,count(*) as cn from t1 group by c1 where cn>1;

17．声明主键和check：一.create table t1(c1 primary key)
二.创建表的时候指定限制的名称:create table t1(c1 constraint pk_emp primary key);
三：create table t1(emp_no number not null , constraint pk_emp primary key(emp_no))； 为已经存在的表增加主键:alter table t1 add constraint pk_emp2 primary key (c1)；
创建check: create table t1(budget number(7),constraint CHK_PROJ check(budget>10000 and budget<1000000))

18.创建外键: create table t1(dept_no varchar2(4) not null, constraint fk_emp foreign key (dept_no) references t2(dept_no), 对已经存在表创建外键:alter table t1
add constraint foreign_work_emp foreign key(c1) references t2(c1)；
  删除一个外键alter table t1  drop constraint foreign_work_emp；


19.删除表：drop table t1; 查看回收站:show recyclebin; 清空回收站 purge recyclebin;
从回收站中恢复数据表:flashback table t1 to before drop;

20.更新数据操作：插入记录：insert into t1(c1,c2)values(‘’,’’)；
插入一字段:insert into t1(c1,c2) select c3,c4 from t2;
更新记录：update t1  set c1=’’ where ;
删除记录：delete from t1 where;truncate table t1;drop table t1;
21.合并查询：intersect(select * intersect select *),union(去掉空),union all(包括空),minus（减集）;
22.多表查询:select * from t1,t2;(笛卡尔集c1行*c2行)；select * from t1 join t2 using(num);等价于select * from t1 inner join t2 on(t1.no=t2.no);join逻辑连接，只连接有联系的字段，full join物理机械连接，out join,left out join(右边变成空),right out join;


23．控制语句：select emp_no, case project_no
when 'p1' then case when enter_date<to_date('1997-10-1','yyyy-mm-dd')then '三室'
when enter_date>to_date('1998-10-1','yyyy-mm-dd')then '等两年'//时间非字段时间型
      else '两室一厅'end
when 'p2' then case when enter_date<to_date('1997-10-1','yyyy-mm-dd')
      then '三室两厅' when enter_date>to_date('1998-10-1','yyyy-mm-dd')
      then '看情况再分' else ' 一室一厅'end
end as 分房情况from works_on；
if then end if,loop end loop,declare type *,while( )loop end loop,case when then end

24.嵌套查询select c1 from t1 where c2 in(select c2 from t2 where c3=(select c3 from t3))


25．Pl/sql语言：模块语法和流程控制：（头控制符没有标点；尾控制符都有；）
declare icount number;
begin
   icount :=0;
   for mycount in reverse 0..10//mycount 为自定义变量
   ---while(icount<100)
   Loop   icount :=icount+10;
   ---exit when(icount>100);
   if(mycount>5) then
    dbms_output.put_line('result='||icount);//流程输出语句
end if;
   end loop;
end; //(set serverout on才能输出)

26．序列Sequence. create sequence se_1 increment by 1 start with 100
maxvalue 999999//minvalue n --表示序列可以生成的最小值(降序). cycle;//到头自动循环
查看：select se_1.nextval from dual; select se_1.currval from dual;（必先next初始化）
使用：create table stu1(stu_no number(10) not null,stu_name varchar2(20) not null);
insert into stu1(stu_no,stu_name) values(se_1.nextval,'joi');
修改序列:alter sequence <sequencen_name>//start with 语句不能用了，否则重复定义
删除序号：drop sequence <sequence_name>；
自动序列rownum:select * from t1 where rownum<5;
select * from(select rownum as a,e.* from t1 e)where a=3//单行必先关联，e为表的别名

27．创建视图create or replace view v1 as
select c1 from t1;
使用视图：select * from v1;

28．创建函数：create or replace function get_maxe_empno return varchar2   is
tmpvar varchar2(20);//局部变量声明
begin //可执行语句
select max(emp_no) into tmpvar from employee;//把取出的值赋给一个变量
return tmpvar;//函数的重要特征就是通过return语句来传递参数
end get_maxe_empno;
使用：select get_maxe_empno() from dual;
数字字典select distinct(name) from user_source where type='FUNCTION'
从数字字典里查找信息：select text from all_source where name='GET_MAXE_EMPNO';
删除函数：drop function get_maxe_empno;


29.过程：create or replace procedure sp_test
(fname in varchar2, update_count out int)//参数列表是过程的特征 is
             cursor emp_cursor//定义游标
             is
             select emp_no from employee where employee.emp_fname=fname;//输入in
         begin        //   可执行语句
     update_count:=0;
     for emp_rec in emp_cursor
     loop
             update employee set emp_fname=emp_lname,emp_lname=fname
     where employee.emp_no=emp_rec.emp_no;update_count:=update_count+1;
     end loop;commit;//控制语句，强制执行
         end；//过程可以有in/out变量
查看过程：select distinct(name) from user_source where type='PROCEDURE'
select text from all_source where name='SP_TEST' order by line;
使用过程：declare fname varchar2(200);
update_count number;
begin
fname:='John';update_count:=0;
sp_test(fname,update_count);commit;dbms_output.put_line(update_count);
end;


30.触发器：create or replace trigger tgr_emp_change
after insert or update or delete on employee
     referencing new as n old as o// :new为引用最新列值;ld为引用以前列值;
   for each row
begin
     if inserting then
     insert into emp_update_info(emp_no,oper_type) values(:n.emp_no,1);
     end if;
     if updating then // updating为触发器的操作符；
     insert into emp_update_info(emp_no,oper_type) values(:o.emp_no,3);
     end if;
end;
建表：create table emp_update_info(emp_no varchar2(20) not null,oper_type integer);
查看trigger：select distinct( name ) from user_source  where type='TRIGGER';
对employee的操作就自动出发的emp_update_info



31．声明包：create or replace package pkg_test as
function get_max_empno   return  varchar2;//子程序说明，公共对象声明
procedure sp_test(fname in varchar2,update_count out int);
end pkg_test;
创建包体:create or replace package body pkg_test as // is也行
           function get_max_empno  return varchar2   as //公共类型与对象声明
          tmpvar    varchar2(20);//公共类型和对象声明，
         begin   // 语句体中是初始化语句，特殊用途
           select max(emp_no) into tmpvar from employee; return tmpvar;
         end get_max_empno;
         //子程序主体部分
           procedure sp_test(fname in varchar2,update_count out int) is
           cursor emp_cursor is
           select emp_no from employee where employee.emp_fname = fname;
           begin
           update_count := 0;
           for emp_rec in emp_cursor
           loop
           update employee set emp_fname = emp_lname, emp_lname = fname
          where employee.emp_no = emp_rec.emp_no;
           update_count := update_count + 1;
           end loop;
           commit;//强制执行
  end;
end pkg_test;
查看定义的package：select distinct( name ) from user_source where type='PACKAGE'
使用package中的对象：select pkg_test.get_max_empno from dual;
32．数据库设计：业务规则和流程—实体和关系—ER图（一对一，一对多，出现多对多进行拆分）—SQL语句—视图和索引—储存过程和触发器—维护。