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:
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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:
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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
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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);
(编辑:李大同)
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