常用sql语句及案例（oracle）

r囧r小猫 2022-05-28 04:30 298阅读 0赞

# 目录 #

[1）基本][1]

[2）数学函数][2]

[3）rownum][3_rownum]

[4）分页][4]

[5）时间处理][5]

[6）字符函数][6]

[7）to\_number][7_to_number]

[8）聚合函数][8]

[9）学生选课][9]

[10）图书馆借阅][10]

# 基本 #

![复制代码][copycode.gif]

--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

![复制代码][copycode.gif]

# 数学函数 #

![复制代码][copycode.gif]

--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;

![复制代码][copycode.gif]

#  rownum相关 #

![复制代码][copycode.gif]

--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

![复制代码][copycode.gif]

#  分页查询 #

（假设每页显示10条）

不包含排序：

![复制代码][copycode.gif]

--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;

![复制代码][copycode.gif]

包含排序：

![复制代码][copycode.gif]

--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;

![复制代码][copycode.gif]

#  时间处理 #

1. to\_char和to\_date基本使用

![复制代码][copycode.gif]

--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

![复制代码][copycode.gif]

eg1:

![复制代码][copycode.gif]

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;

![复制代码][copycode.gif]

![021239281117035.png][]

eg2:

![复制代码][copycode.gif]

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;

![复制代码][copycode.gif]

![021241046898907.png][]

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;

![021251407368422.png][]

3)next\_day

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

![021258277671039.png][]

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

按 Ctrl+C 复制代码

![021315497522671.png][]

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;

![021327153773967.png][]

# 字符函数 #

![复制代码][copycode.gif]

--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;

![复制代码][copycode.gif]

![021357458459884.png][]

# to\_number #

![复制代码][copycode.gif]

--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;

![复制代码][copycode.gif]

![021454176111823.png][]

# 聚合函数 #

student表如下：

![021516387364977.png][]

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：

![021518052679411.png][]

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）

![复制代码][copycode.gif]

--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  
    );

![复制代码][copycode.gif]

2.插入数据

![复制代码][copycode.gif]

--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);

![复制代码][copycode.gif]

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：

![301515564701358.png][]

# 案例2--图书馆借阅 #

1.创建表： 图书（book），读者（reader），借阅（borrow）

![复制代码][copycode.gif]

--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
    );

![复制代码][copycode.gif]

2.插入数据

![复制代码][copycode.gif]

--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,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-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');

![复制代码][copycode.gif]

表信息如下：

book------> reader-------> borrow

![301157317673204.png][]

![301156457678283.png][]

![301157597835497.png][]

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);

![301155532207230.png][]

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);

![301155095955469.png][]

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';

![301200576581872.png][]

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 gender
    from reader where name like 'm%';

![301205549703335.png][]

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：

![301454349236704.png][]

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');

![301455218454539.png][]

3）查询+去重+读者姓名等信息

![复制代码][copycode.gif]

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);

![复制代码][copycode.gif]

![301456221588899.png][]

[1]: https://www.cnblogs.com/wishyouhappy/p/3700683.html#basic
[2]: https://www.cnblogs.com/wishyouhappy/p/3700683.html#math
[3_rownum]: https://www.cnblogs.com/wishyouhappy/p/3700683.html#rownum
[4]: https://www.cnblogs.com/wishyouhappy/p/3700683.html#pag
[5]: https://www.cnblogs.com/wishyouhappy/p/3700683.html#time
[6]: https://www.cnblogs.com/wishyouhappy/p/3700683.html#char
[7_to_number]: https://www.cnblogs.com/wishyouhappy/p/3700683.html#tonumber
[8]: https://www.cnblogs.com/wishyouhappy/p/3700683.html#agg
[9]: https://www.cnblogs.com/wishyouhappy/p/3700683.html#student
[10]: https://www.cnblogs.com/wishyouhappy/p/3700683.html#lib
[copycode.gif]: /images/20220528/70927cecf5e24a90a9c6d928d7b0160c.png
[021239281117035.png]: /images/20220528/e92d6f3e99a54e028aa803375de64827.png
[021241046898907.png]: /images/20220528/177415ca9ba045debe4f8dd0bae5b4e8.png
[021251407368422.png]: /images/20220528/ff5adbe0e9bd4e9fbbf18dbdb18cf35e.png
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