常用sql语句及案例（oracle）

2023-08-13 11:49:46

目录

1）基本

2）数学函数

3）rownum

4）分页

5）时间处理

6）字符函数

7）to_number

8）聚合函数

9）学生选课

10）图书馆借阅

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;

常用sql语句及案例（oracle）

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;

常用sql语句及案例（oracle）

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;

常用sql语句及案例（oracle）

3)next_day

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

常用sql语句及案例（oracle）

4)时间区间

eg：

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 '' year,'yyyy-mm-dd hh24:mi:ss') intervalyear,

       to_char(sysdate - interval '' month,'yyyy-mm-dd hh24:mi:ss') intervalMonth,

       to_char(sysdate - interval '' day,'yyyy-mm-dd hh24:mi:ss') intervalday,

       to_char(sysdate - interval '' hour,'yyyy-mm-dd hh24:mi:ss') intervalHour,

       to_char(sysdate - interval '' minute,'yyyy-mm-dd hh24:mi:ss') intervalMinute,

       to_char(sysdate - interval '' second,'yyyy-mm-dd hh24:mi:ss') intervalSecond

  from dual;

常用sql语句及案例（oracle）

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;

常用sql语句及案例（oracle）

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','','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('','') concat          　　　　　　　　   --连接

from dual;

常用sql语句及案例（oracle）

to_number

--to_number(expr)

--to_number(expr,format)

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

select to_number('')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;

常用sql语句及案例（oracle）

聚合函数

student表如下：

常用sql语句及案例（oracle）

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：

常用sql语句及案例（oracle）

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：

常用sql语句及案例（oracle）

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','');

insert into book (bookId,sortid,bookname,author,publisher,price)

values ('bbb','a2','the little prince','CB','jixie','');

insert into book (bookId,sortid,bookname,author,publisher,price)

values ('ccc','a3','the ordinary world','CC','renmin','');

insert into book (bookId,sortid,bookname,author,publisher,price)

values ('ddd','a4','the little women','CA','dianzi','');

--插入数据-reader

insert into reader(cardid, org, name,gender, title, address)

values ('xxx','A','wish','','student','bupt');

insert into reader(cardid, org, name,gender, title, address)

values ('uuu','A','luna','','student','bupt');

insert into reader(cardid, org, name,gender, title, address)

values ('vvv','B','harry','','student','bupt');

insert into reader(cardid, org, name,gender, title, address)

values ('www','C','chander','','professor','bupt');

insert into reader(cardid, org, name,gender, title, address)

values ('yyy','A','joey','','student','bupt');

insert into reader(cardid, org, name,gender, title, address)

values ('zzz','B','richard','','student','bupt');

insert into reader(cardid, org, name,gender, title, address)

values ('OOO','A','micheal','','student','bupt');

insert into reader(cardid, org, name,gender, title, address)

values ('ppp','A','richal','','student','bupt');

insert into reader(cardid, org, name,gender, title, address)

values ('abp','A','michal','','student','bupt');

insert into reader(cardid, org, name,gender, title, address)

values ('ccp','A','mike','','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

常用sql语句及案例（oracle）

常用sql语句及案例（oracle）

常用sql语句及案例（oracle）

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);

常用sql语句及案例（oracle）

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);

常用sql语句及案例（oracle）

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';

常用sql语句及案例（oracle）

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='' then '女' when gender='' then '男' else '其他' end gender

from reader where name like 'm%';

常用sql语句及案例（oracle）

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')=''

and to_char(to_date(borrowdate,'yyyy-mm-dd'),'mm')>=''

and to_char(to_date(borrowdate,'yyyy-mm-dd'),'mm')<='';

　　方式二：

select cardid, borrowdate from borrow where to_char(to_date(borrowdate,'yyyy-mm-dd'),'yyyy')=''  --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');

常用sql语句及案例（oracle）

2) 查询+去重

select distinct cardid from borrow where to_char(to_date(borrowdate,'yyyy-mm-dd'),'yyyy')=''  --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');

常用sql语句及案例（oracle）

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')=''

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);

常用sql语句及案例（oracle）

上一篇：另类的package-info.java文件探讨


下一篇：Java-HttpServletRequest