常用sql语句及案例（oracle）

原文：http://www.cnblogs.com/wishyouhappy/p/3700683.html

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1select * 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2select * 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') secondfrom 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') secondfrom 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

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 '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

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

 

sum

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

 

median--中位数

--medianselect 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 bookcreate 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 borrowcreate 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-bookinsert 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-readerinsert 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-borrowinsert 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 genderfrom 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);