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Oraclle数据库常用语法

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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(-1,3,5,7,9) 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,
to_char(sysdate,'mm') month,
to_char(sysdate,'dd') day,
to_char(sysdate,'day') week,
to_char(sysdate,'hh24')hour,
to_char(sysdate,'mi') minute,
to_char(sysdate,'ss') second
from dual;


eg2:

select to_date('2009-07-04 05:02:01','yyyy-mm-dd hh24:mi:ss')currenttime,
to_char(to_date('2009-07-04 05:02:01','yyyy-mm-dd hh24:mi:ss'),'yyyy')year,
to_char(to_date('2009-07-04 05:02:01','yyyy-mm-dd hh24:mi:ss'),'mm')month,
to_char(to_date('2009-07-04 05:02:01','yyyy-mm-dd hh24:mi:ss'),'dd') day,
to_char(to_date('2009-07-04 05:02:01','yyyy-mm-dd hh24:mi:ss'),'day') week,
to_char(to_date('2009-07-04 05:02:01','yyyy-mm-dd hh24:mi:ss'),'day','NLS_DATE_LANGUAGE=American') week, --设置语言
to_char(to_date('2009-07-04 05:02:01','yyyy-mm-dd hh24:mi:ss'),'hh24')hour,
to_char(to_date('2009-07-04 05:02:01','yyyy-mm-dd hh24:mi:ss'),'mi') minute,
to_char(to_date('2009-07-04 05:02:01','yyyy-mm-dd hh24:mi:ss'),'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','1','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 (1,1,80);
Insert into S_C (SID,CID,SCORE) values (1,2,90);
Insert into S_C (SID,CID,SCORE) values (2,4,100);
Insert into S_C (SID,CID,SCORE) values (4,4,90);
Insert into S_C (SID,CID,SCORE) values (4,1,100);
Insert into S_C (SID,CID,SCORE) values (4,3,80);
Insert into S_C (SID,CID,SCORE) values (4,2,80);
Insert into S_C (SID,CID,SCORE) values (2,1,90);
Insert into S_C (SID,CID,SCORE) values (2,4,100);
Insert into S_C (SID,CID,SCORE) values (3,1,60);


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,sortid,bookname,author,publisher,price) 
values ('bbb','a2','the little prince','CB','jixie','30');

insert into book (bookId,sortid,bookname,author,publisher,price) 
values ('ccc','a3','the ordinary world','CC','renmin','130');

insert into book (bookId,sortid,bookname,author,publisher,price) 
values ('ddd','a4','the little women','CA','dianzi','110');

--插入数据-reader
insert into reader(cardid, org, name,gender, title, address)
values ('xxx','A','wish','1','student','bupt');

insert into reader(cardid, org, name,gender, title, address)
values ('uuu','A','luna','1','student','bupt');

insert into reader(cardid, org, name,gender, title, address)
values ('vvv','B','harry','1','student','bupt');

insert into reader(cardid, org, name,gender, title, address)
values ('www','C','chander','2','professor','bupt');

insert into reader(cardid, org, name,gender, title, address)
values ('yyy','A','joey','2','student','bupt');

insert into reader(cardid, org, name,gender, title, address)
values ('zzz','B','richard','2','student','bupt');

insert into reader(cardid, org, name,gender, title, address)
values ('OOO','A','micheal','2','student','bupt');

insert into reader(cardid, org, name,gender, title, address)
values ('ppp','A','richal','2','student','bupt');

insert into reader(cardid, org, name,gender, title, address)
values ('abp','A','michal','2','student','bupt');

insert into reader(cardid, org, name,gender, title, address)
values ('ccp','A','mike','2','student','bupt');
--插入数据-borrow
insert into borrow(cardid,bookid,borrowdate) values('xxx','aaa','2014-4-29');
insert into borrow(cardid,bookid,borrowdate) values('xxx','bbb','2014-4-29');
insert into borrow(cardid,bookid,borrowdate) values('xxx','ccc','2014-4-28');
insert into borrow(cardid,bookid,borrowdate) values('yyy','ccc','2014-4-28');
insert into borrow(cardid,bookid,borrowdate) values('yyy','ddd','2014-4-27');
insert into borrow(cardid,bookid,borrowdate) values('yyy','aaa','2014-4-27');
insert into borrow(cardid,bookid,borrowdate) values('zzz','bbb','2014-4-28');
insert into borrow(cardid,bookid,borrowdate) values('zzz','ddd','2014-4-27');
insert into borrow(cardid,bookid,borrowdate) values('zzz','aaa','2014-4-27');
insert into borrow(cardid,bookid,borrowdate) values('uuu','bbb','2014-4-28');
insert into borrow(cardid,bookid,borrowdate) values('uuu','ddd','2014-4-27');
insert into borrow(cardid,bookid,borrowdate) values('uuu','aaa','2014-4-27');
insert into borrow(cardid,bookid,borrowdate) values('uuu','ccc','2014-4-26');
insert into borrow(cardid,bookid,borrowdate) values('vvv','bbb','2014-4-28');
insert into borrow(cardid,bookid,borrowdate) values('vvv','ddd','2014-4-27');
insert into borrow(cardid,bookid,borrowdate) values('www','aaa','2014-4-27');
insert into borrow(cardid,bookid,borrowdate) values('www','ccc','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,name,org from reader where reader.org='A')
select cardid,name,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, name, 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, name, org, 
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,'yyyy-mm-dd'),'mm')>='02'
and to_char(to_date(borrowdate,'yyyy-mm-dd'),'mm')<='04';
方式二:

select cardid, borrowdate from borrow where to_char(to_date(borrowdate,'yyyy-mm-dd'),'yyyy')='2014' --查询
and to_char(to_date(borrowdate,'yyyy-mm-dd'),'yyyy-mm')>='2014-02'
and to_char(to_date(borrowdate,'yyyy-mm-dd'),'yyyy-mm')<='2014-04';
方式三:

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');


2) 查询+去重

select distinct cardid from borrow where to_char(to_date(borrowdate,'yyyy-mm-dd'),'yyyy')='2014' --查询+去重
and to_char(to_date(borrowdate,'yyyy-mm-dd'),'yyyy-mm')>='2014-02'
and to_char(to_date(borrowdate,'yyyy-mm-dd'),'yyyy-mm')<='2014-04';
select distinct cardid 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');


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-mm-dd'),'yyyy')='2014' 
and to_char(to_date(borrowdate,'yyyy-mm-dd'),'yyyy-mm')>='2014-02'
and to_char(to_date(borrowdate,'yyyy-mm-dd'),'yyyy-mm')<='2014-04')
select cardid, name,org from reader where exists (select cardid from vt1 where vt1.cardid=reader.cardid);

 

标签:yyyy,Oraclle,--,数据库,语法,values,cardid,into,select
来源: https://blog.csdn.net/weixin_45452000/article/details/122696122