Oracle数据库常用语法

基本
--新建表：
create table table1( id varchar(300) primary key,name varchar(200) not null);

--插入数据
insert into table1 (id,name) values (‘aa‘,‘bb‘);

--更新数据
update table1 set id = ‘bb‘ where id=‘cc‘;

--删除数据
delete from table1 where id =‘cc‘;

--删除表
drop table table1;

--修改表名：
alter table table1 rename to table2;

--表数据复制：
insert into table1 (select * from table2);

--复制表结构：
create table table1 select * from table2 where 1>1;

--复制表结构和数据：
create table table1 select * from table2;

--复制指定字段：
create table table1 as select id,name from table2 where 1>1;

--条件查询：
select id,name (case gender when 0 then ‘男‘ when 1 then ‘女’ end ) gender from table1
数学函数
--绝对值：abs()
select abs(-2) value from dual; --(2)

--取整函数（大）：ceil（）
select ceil(-2.001) value from dual; --(-2)

--取整函数（小）：floor（）
select floor(-2.001) value from dual; --(-3)

--取整函数（截取）：trunc（）
select trunc(-2.001) value from dual; -- (-2)

--四舍五入：round（）
select round(1.234564,4) value from dual; --(1.2346)

--取平方：Power（m,n）
select power(4,2) value from dual; --(16)

--取平方根:SQRT()
select sqrt(16) value from dual; --(4)

--取随机数:dbms_random(minvalue,maxvalue)
select dbms_random.value() from dual; (默认是0到1之间)
　select dbms_random.value(2,4) value from dual; （2-4之间随机数）

--取符号：Sign()
　　select sign(-3) value from dual; --(-1)
　　select sign(3) value from dual; --(1)

--取集合的最大值:greatest(value)
select greatest(-1,3,5,7,9) value from dual; --(9)

--取集合的最小值:least(value)
select least(-1,9) value from dual; --(-1)

--处理Null值：nvl(空值，代替值)
select nvl(null,10) value from dual; --(10)
　　
select nvl(score,10) score from student;
rownum相关
--rownum小于某个数时可以直接作为查询条件（注意oracle不支持select top）
select * from student where rownum <3;

--查询rownum大于某个数值,需要使用子查询，并且rownum需要有别名
select * from(select rownum rn,id,name from student) where rn>2;
select * from (select rownum rn,student.* from student) where rn >3;

--区间查询
select * from (select rownum rn,student.* from student) where rn >3 and rn<6;

--排序+前n条
select * from (select rownum rn,t.* from ( select d.* from DJDRUVER d order by drivernumber)t )p where p.rn<10;

--排序+区间查询1
select * from (select rownum rn,t.* from ( select d.* from DJDRIVER d order by DJDRIVER_DRIVERTIMES)t )p where p.rn<9 and p.rn>6;

--排序+区间查询2
select * from (select rownum rn,t.* from ( select d.* from DJDRIVER d order by DJDRIVER_DRIVERTIMES)t where rownum<9 )p where p.rn>6;--效率远高于方式一
 分页查询
（假设每页显示10条）

不包含排序：

--效率低

select * from (select rownum rn,d.* from DJDRIVER d )p where p.rn<=20 and p.rn>=10;

select * from (select rownum rn,d.* from DJDRIVER d )p where p.rn between 10 and 20;

--效率高

select * from (select rownum rn,d.* from DJDRIVER d where rownum<=20 )p where p.rn>=10;
包含排序：
--排序+区间查询1（效率低）

select * from (select rownum rn,t.* from ( select d.* from DJDRIVER d order by DJDRIVER_DRIVERTIMES)t )p where p.rn<=20 and p.rn>=10;

select * from (select rownum rn,t.* from ( select d.* from DJDRIVER d order by DJDRIVER_DRIVERTIMES)t )p where p.rn between 10 and 20;

--排序+区间查询2（效率高）

select * from (select rownum rn,t.* from ( select d.* from DJDRIVER d order by DJDRIVER_DRIVERTIMES)t where rownum<=20 )p where p.rn>=10;
 时间处理
1. to_char和to_date基本使用

--日期
--年 yyyy yyy yy year
--月 month mm mon month
--日+星期 dd ddd(一年中第几天) dy day
--小时 hh hh24
--分 mi
--秒 ss

eg1:
select to_char(sysdate,‘yyyy-mm-dd hh24:mi:ss‘)currenttime,
to_char(sysdate,‘yyyy‘) year,‘mm‘) month,‘dd‘) day,‘day‘) week,‘hh24‘)hour,‘mi‘) minute,‘ss‘) second
from dual;

eg2:

select to_date(‘2009-07-04 05:02:01‘,
to_char(to_date(‘2009-07-04 05:02:01‘,‘yyyy-mm-dd hh24:mi:ss‘),‘yyyy‘)year,‘mm‘)month,‘day‘,‘NLS_DATE_LANGUAGE=American‘) week,--设置语言
to_char(to_date(‘2009-07-04 05:02:01‘,‘ss‘) second
from dual;

2）months_between

select months_between(to_date(‘03-31-2014‘,‘MM-DD-YYYY‘),to_date(‘12-31-2013‘,‘MM-DD-YYYY‘)) "MONTHS"
FROM DUAL;

3)next_day

select sysdate today,next_day(sysdate,6) nextweek from dual;

4)时间区间

例：

select cardid,borrowdate from borrow where to_date(borrowdate,‘yyyy-mm-dd hh24:mi:ss‘) between
to_date(‘2014-02-01 00:00:00‘,‘yyyy-mm-dd hh24:mi:ss‘) and
to_date(‘2014-05-01 00:00:00‘,‘yyyy-mm-dd hh24:mi:ss‘);

5）interval

select to_char(sysdate,‘yyyy-mm-dd hh24:mi:ss‘) currenttime,
to_char(sysdate - interval ‘7‘ year,‘yyyy-mm-dd hh24:mi:ss‘) intervalyear,
to_char(sysdate - interval ‘7‘ month,‘yyyy-mm-dd hh24:mi:ss‘) intervalMonth,
to_char(sysdate - interval ‘7‘ day,‘yyyy-mm-dd hh24:mi:ss‘) intervalday,
to_char(sysdate - interval ‘7‘ hour,‘yyyy-mm-dd hh24:mi:ss‘) intervalHour,
to_char(sysdate - interval ‘7‘ minute,‘yyyy-mm-dd hh24:mi:ss‘) intervalMinute,
to_char(sysdate - interval ‘7‘ second,‘yyyy-mm-dd hh24:mi:ss‘) intervalSecond
from dual;

6）add_months

select add_months(sysdate,12) newtime from dual;
7)extract

select extract(month from sysdate) "This Month",
extract(year from add_months(sysdate,36)) " Years" from dual;

字符函数
--字符函数
select substr(‘abcdefg‘,1,5)substr,--字符串截取
instr(‘abcdefg‘,‘bc‘) instr,--查找子串

‘Hello‘||‘World‘ concat,--连接

trim(‘ wish ‘) trim,--去前后空格
rtrim(‘wish ‘) rtrim,--去后面空格
ltrim(‘ wish‘) ltrim,--去前面空格

trim(leading ‘w‘ from ‘wish‘) deleteprefix,--去前缀
trim(trailing ‘h‘ from ‘wish‘) deletetrailing,--去后缀
trim(‘w‘ from ‘wish‘) trim1,

ascii(‘A‘) A1,
ascii(‘a‘) A2,--ascii(转换为对应的十进制数)
chr(65) C1,
chr(97) C2,--chr(十进制转对应字符)

length(‘abcdefg‘) len,--length

lower(‘WISH‘)lower,
upper(‘wish‘)upper,
initcap(‘wish‘)initcap,--大小写变换

replace(‘wish1‘,‘1‘,‘youhappy‘) replace,--替换

translate(‘wish1‘,‘y‘)translate,--转换，对应一位(前面的位数大于等于后面的位数)
translate(‘wish1‘,‘sh1‘,‘hy‘)translate1,

concat(‘11‘,‘22‘) concat 　　　　　　　　 --连接

from dual;

to_number
--to_number(expr)
--to_number(expr,format)
--to_number(expr,format,‘nls-param‘)

select to_number(‘0123‘)number1,--converts a string to number
trunc(to_number(‘0123.123‘),2) number2,
to_number(‘120.11‘,‘999.99‘) number3,
　　　 to_number(‘0a‘,‘xx‘) number4,--converts a hex number to decimal
to_number(100000,‘xxxxxx‘) number5

from dual;

聚合函数
student表如下：

count：

--count (distinct|all)
select count(1) as count from student;--效率最高
select count(*) as count from student;
select count(distinct score) from student;
语句1结果：11

avg

--avg (distinct|all)
select avg(score) score from student;
select avg(distinct score) from student;
select classno,avg(score) score from student group by classno;
语句3输出结果：

 

max

--max (distinct|all)
select max(score) from student;
select classno,max(score) score from student group by classno;
min

--min (distinct|all)
select min(score) from student;
select classno,min(score) score from student group by classno;
stddev（standard deviation）标准差

--stddev
select stddev(score) from student;
select classno,stddev(score) score from student group by classno;
sum

--sum
select sum(score) from student;
select classno,sum(score) score from student group by classno;
median--中位数

--median
select median(score) from student;
select classno,median(score) score from student group by classno;
 案例1--学生选课
1. 创建表 stu（学生表），course（课程表），选课表（s_c）

--创建表

create table STU
(
id NUMBER not null,
name VARCHAR2(255)
) ;

create table COURSE
(
id NUMBER not null,
coursename VARCHAR2(255)
) ;

create table S_C
(
sid NUMBER,
cid NUMBER,
score NUMBER
);
2.插入数据

--插入数据
Insert into STU (ID,NAME) values (1,‘wish‘);
Insert into STU (ID,NAME) values (2,‘rain‘);
Insert into STU (ID,NAME) values (3,‘july‘);
Insert into STU (ID,NAME) values (4,‘joey‘);

Insert into COURSE (ID,COURSENAME) values (1,‘math‘);
Insert into COURSE (ID,COURSENAME) values (2,‘english‘);
Insert into COURSE (ID,COURSENAME) values (3,‘Japanese‘);
Insert into COURSE (ID,COURSENAME) values (4,‘chinese‘);

Insert into S_C (SID,CID,SCORE) values (1,80);
Insert into S_C (SID,2,90);
Insert into S_C (SID,SCORE) values (2,4,100);
Insert into S_C (SID,SCORE) values (4,SCORE) values (3,60);
3.查询学生选课情况

with vt as
(select s.id,s.name,c.coursename,sc.score from stu s,course c,s_c sc where s.id=sc.sid and c.id=sc.cid)
select * from vt order by id;
结果：

 

案例2--图书馆借阅
1.创建表： 图书（book），读者（reader），借阅（borrow）

--创建表 book
create table book(
bookId varchar2(30),--图书总编号
sortid varchar2(30),--分类号
bookname varchar2(100),--书名
author varchar2(30),--作者
publisher varchar2(100),--出版单位
price number(6,2) --价格
);

--创建表 reader
create table reader (
cardId varchar2(30),--借书证号
org varchar2(100),--单位
name varchar2(100),--姓名
gender varchar2(2),--性别
title varchar2(30),--职称
address varchar2(100) --地址
);

--创建表 borrow
create table borrow(
cardId varchar2(30),--借书证号
bookId varchar2(30),--图书总编号
borrowDate varchar2(30) --借阅时间
);
2.插入数据

--插入数据-book
insert into book (bookId,sortid,bookname,author,publisher,price)
values (‘aaa‘,‘a1‘,‘gone with the wind‘,‘CA‘,‘renmin‘,‘103‘);

insert into book (bookId,price)
values (‘bbb‘,‘a2‘,‘the little prince‘,‘CB‘,‘jixie‘,‘30‘);

insert into book (bookId,price)
values (‘ccc‘,‘a3‘,‘the ordinary world‘,‘CC‘,‘130‘);

insert into book (bookId,price)
values (‘ddd‘,‘a4‘,‘the little women‘,‘dianzi‘,‘110‘);

--插入数据-reader
insert into reader(cardid,org,name,gender,title,address)
values (‘xxx‘,‘A‘,‘wish‘,‘student‘,‘bupt‘);

insert into reader(cardid,address)
values (‘uuu‘,‘luna‘,address)
values (‘vvv‘,‘B‘,‘harry‘,address)
values (‘www‘,‘C‘,‘chander‘,‘2‘,‘professor‘,address)
values (‘yyy‘,‘joey‘,address)
values (‘zzz‘,‘richard‘,address)
values (‘OOO‘,‘micheal‘,address)
values (‘ppp‘,‘richal‘,address)
values (‘abp‘,‘michal‘,address)
values (‘ccp‘,‘mike‘,‘bupt‘);
--插入数据-borrow
insert into borrow(cardid,bookid,borrowdate) values(‘xxx‘,‘aaa‘,‘2014-4-29‘);
insert into borrow(cardid,‘bbb‘,‘ccc‘,‘2014-4-28‘);
insert into borrow(cardid,borrowdate) values(‘yyy‘,‘ddd‘,‘2014-4-27‘);
insert into borrow(cardid,borrowdate) values(‘zzz‘,borrowdate) values(‘uuu‘,‘2014-4-26‘);
insert into borrow(cardid,borrowdate) values(‘vvv‘,borrowdate) values(‘www‘,‘2014-4-26‘);
表信息如下：

book------> reader-------> borrow

 

 

 

3. 查询A单位借阅图书的读者人数和人员详细信息

人数：

with vt1 as
(select cardid from reader where reader.org=‘A‘)
select count(1) from vt1 where exists (select cardid from borrow where borrow.cardid=vt1.cardid);

详细信息：

with vt1 as
(select cardid,org from reader where reader.org=‘A‘)
select cardid,org from vt1 where exists (select cardid from borrow where borrow.cardid=vt1.cardid);

4.查询借书证号尾字符为‘p‘的读者

select cardid,org from reader where cardid like ‘%p‘;

5. 查询名字以m开头的女性读者，‘1’显示为女，‘2’显示为男

select cardid,
case when gender=‘1‘ then ‘女‘ when gender=‘2‘ then ‘男‘ else ‘其他‘ end gender
from reader where name like ‘m%‘;

6. 2014年2-4月借过书的读者

1)查询满足条件的读者（仅包含cardid）--未去重

　　方式一：

select cardid,borrowdate from borrow where to_char(to_date(borrowdate,‘yyyy-mm-dd‘),‘yyyy‘)=‘2014‘
and to_char(to_date(borrowdate,‘mm‘)>=‘02‘
and to_char(to_date(borrowdate,‘mm‘)<=‘04‘;
方式二：

select cardid,‘yyyy‘)=‘2014‘ --查询
and to_char(to_date(borrowdate,‘yyyy-mm‘)>=‘2014-02‘
and to_char(to_date(borrowdate,‘yyyy-mm‘)<=‘2014-04‘;
方式三：

select cardid,‘yyyy-mm-dd hh24:mi:ss‘);

2) 查询+去重

select distinct cardid from borrow where to_char(to_date(borrowdate,‘yyyy‘)=‘2014‘ --查询+去重
and to_char(to_date(borrowdate,‘yyyy-mm‘)<=‘2014-04‘;
select distinct cardid from borrow where to_date(borrowdate,‘yyyy-mm-dd hh24:mi:ss‘);

3）查询+去重+读者姓名等信息

with vt1 as (select distinct cardid from borrow where to_char(to_date(borrowdate,‘yyyy‘)=‘2014‘ and to_char(to_date(borrowdate,‘yyyy-mm‘)>=‘2014-02‘and to_char(to_date(borrowdate,‘yyyy-mm‘)<=‘2014-04‘)select cardid,org from reader where exists (select cardid from vt1 where vt1.cardid=reader.cardid);