常用sql語句及案例（oracle）

目錄

1）基本

2）數學函數

3）rownum

4）分頁

5）時間處理

6）字符函數

7）to_number

8）聚合函數

9）學生選課

10）圖書館借閱

 

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;
 
--表數據復制：
insert into table1 (select * from table2);
 
--復制表結構： 
create table table1 select * from table2 where 1>1;
 
--復制表結構和數據：
create table table1 select * from table2;
 
--復制指定字段： 
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為查詢條件（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,      --去前綴
       trim(trailing 'h' from 'wish') deletetrailing,   --去后綴
       trim('w' from 'wish') trim1,
       
       ascii('A') A1, 
       ascii('a') A2,                                   --ascii(轉換為對應的十進制數)
       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后面的位數)
       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為'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’顯示為女，‘2’顯示為男

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);