基本
--新建表:
create table table1( id varchar(300) primary key, name varchar(200) not null);
--插入數據
insert into table1 (id,name) values ('aa','bb');
--更新數據
update table1 set id = 'bb' where id='cc';
--刪除數據
delete from table1 where id ='cc';
--刪除表
drop table table1;
--修改表名:
alter table table1 rename to table2;
--表數據複製:
insert into table1 (select * from table2);
--複製表結構:
create table table1 select * from table2 where 1>1;
--複製表結構和數據:
create table table1 select * from table2;
--複製指定字段:
create table table1 as select id, name from table2 where 1>1;
--條件查詢:
select id,name (case gender when 0 then '男' when 1 then ‘女’ end ) gender from table1
數學函數
--絕對值:abs()
select abs(-2) value from dual; --(2)
--取整函數(大):ceil()
select ceil(-2.001) value from dual; --(-2)
--取整函數(小):floor()
select floor(-2.001) value from dual; --(-3)
--取整函數(截取):trunc()
select trunc(-2.001) value from dual; -- (-2)
--四捨五入: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)
--取隨機數:dbms_random(minvalue,maxvalue)
select dbms_random.value() from dual; (默認是0到1之間)
select dbms_random.value(2,4) value from dual; (2-4之間隨機數)
--取符號: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)
--處理Null值:nvl(空值,代替值)
select nvl(null,10) value from dual; --(10)
select nvl(score,10) score from student;
rownum相關
--rownum小於某個數時可以直接作爲查詢條件(注意oracle不支持select top)
select * from student where rownum <3;
--查詢rownum大於某個數值,需要使用子查詢,並且rownum需要有別名
select * from(select rownum rn ,id,name from student) where rn>2;
select * from (select rownum rn, student.* from student) where rn >3;
--區間查詢
select * from (select rownum rn, student.* from student) where rn >3 and rn<6;
--排序+前n條
select * from (select rownum rn, t.* from ( select d.* from DJDRUVER d order by drivernumber)t )p where p.rn<10;
--排序+區間查詢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+區間查詢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;--效率遠高於方式一
分頁查詢
(假設每頁顯示10條)
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+區間查詢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+區間查詢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;
時間處理
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(一年中第幾天) dy day
--小時 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, --設置語言
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)時間區間
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;
字符函數
--字符函數
select substr('abcdefg',1,5)substr, --字符串截取
instr('abcdefg','bc') instr, --查找子串
'Hello'||'World' concat, --連接
trim(' wish ') trim, --去前後空格
rtrim('wish ') rtrim, --去後面空格
ltrim(' wish') ltrim, --去前面空格
trim(leading 'w' from 'wish') deleteprefix, --去前綴
trim(trailing 'h' from 'wish') deletetrailing, --去後綴
trim('w' from 'wish') trim1,
ascii('A') A1,
ascii('a') A2, --ascii(轉換爲對應的十進制數)
chr(65) C1,
chr(97) C2, --chr(十進制轉對應字符)
length('abcdefg') len, --length
lower('WISH')lower,
upper('wish')upper,
initcap('wish')initcap, --大小寫變換
replace('wish1','1','youhappy') replace, --替換
translate('wish1','1','y')translate, --轉換,對應一位(前面的位數大於等於後面的位數)
translate('wish1','sh1','hy')translate1,
concat('11','22') concat --連接
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;
聚合函數
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;
語句1結果: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;
語句3輸出結果:
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)標準差
--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--中位數
--median
select median(score) from student;
select classno, median(score) score from student group by classno;
案例1--學生選課
1. 創建表 stu(學生表),course(課程表),選課表(s_c)
--創建表
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.插入數據
--插入數據
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.查詢學生選課情況
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;
結果:
案例2--圖書館借閱
1.創建表: 圖書(book),讀者(reader),借閱(borrow)
--創建表 book
create table book(
bookId varchar2(30), --圖書總編號
sortid varchar2(30), --分類號
bookname varchar2(100), --書名
author varchar2(30), --作者
publisher varchar2(100),--出版單位
price number(6,2) --價格
);
--創建表 reader
create table reader (
cardId varchar2(30), --借書證號
org varchar2(100), --單位
name varchar2(100), --姓名
gender varchar2(2), --性別
title varchar2(30), --職稱
address varchar2(100) --地址
);
--創建表 borrow
create table borrow(
cardId varchar2(30), --借書證號
bookId varchar2(30), --圖書總編號
borrowDate varchar2(30) --借閱時間
);
2.插入數據
--插入數據-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');
--插入數據-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');
--插入數據-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. 查詢A單位借閱圖書的讀者人數和人員詳細信息
人數:
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);
詳細信息:
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.查詢借書證號尾字符爲'p'的讀者
select cardid, name, org from reader where cardid like '%p';
5. 查詢名字以m開頭的女性讀者,‘1’顯示爲女,‘2’顯示爲男
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月借過書的讀者
1)查詢滿足條件的讀者(僅包含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' --查詢
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) 查詢+去重
select distinct cardid from borrow where to_char(to_date(borrowdate,'yyyy-mm-dd'),'yyyy')='2014' --查詢+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)查詢+去重+讀者姓名等信息
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);