首页 > 代码库 > 常用sql语句及案例(oracle)

常用sql语句及案例(oracle)

 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

 

1)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‘;
 
--删除表结构   
drop table table1;
 
--删除表数据   
truncate 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

 

2)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;

 

3)rownum
--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

 

4)分页
(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;

 

5)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

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;

技术分享


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;

技术分享

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;

技术分享

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

技术分享

4.时间区间
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;

技术分享


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;

 技术分享

 

 6)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,                              --长度
       
       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;

技术分享

 

7)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;

技术分享

 

 

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; 

常用sql语句及案例(oracle)