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oracle常用sql语句

2017-08-09

oracle常用sql语句。1)基本

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    
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 

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
-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

--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,&#39;yyyy-mm-dd hh24:mi:ss&#39;)currenttime, 
       to_char(sysdate,&#39;yyyy&#39;) year,
       to_char(sysdate,&#39;mm&#39;) month,
       to_char(sysdate,&#39;dd&#39;) day,
       to_char(sysdate,&#39;day&#39;) week,
       to_char(sysdate,&#39;hh24&#39;)hour,
       to_char(sysdate,&#39;mi&#39;) minute,
       to_char(sysdate,&#39;ss&#39;) second
from dual;

这里写图片描述

months_between

 select months_between(to_date(&#39;03-31-2014&#39;,&#39;MM-DD-YYYY&#39;),to_date(&#39;12-31-2013&#39;,&#39;MM-DD-YYYY&#39;)) "MONTHS"
 FROM DUAL; 

这里写图片描述

next_day

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

这里写图片描述

add_months

select add_months(sysdate,12) newtime from dual;


extract

 select extract(month from sysdate) "This Month",
extract(year from add_months(sysdate,36)) " Years" from dual; 

这里写图片描述

6)字符函数

--字符函数
select substr(&#39;abcdefg&#39;,1,5)substr,                     --字符串截取
       instr(&#39;abcdefg&#39;,&#39;bc&#39;) instr,                     --查找子串

       &#39;Hello&#39;||&#39;World&#39; concat,                         --连接

       trim(&#39;  wish  &#39;) trim,                           --去前后空格
       rtrim(&#39;wish  &#39;) rtrim,                           --去后面空格
       ltrim(&#39;  wish&#39;) ltrim,                           --去前面空格

       trim(leading &#39;w&#39; from &#39;wish&#39;) deleteprefix,      --去前缀
       trim(trailing &#39;h&#39; from &#39;wish&#39;) deletetrailing,   --去后缀
       trim(&#39;w&#39; from &#39;wish&#39;) trim1,

       ascii(&#39;A&#39;) A1, 
       ascii(&#39;a&#39;) 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(&#39;abcdefg&#39;) len,                           --length 

       lower(&#39;WISH&#39;)lower, 
       upper(&#39;wish&#39;)upper, 
       initcap(&#39;wish&#39;)initcap,                            --大小写变换

       replace(&#39;wish1&#39;,&#39;1&#39;,&#39;youhappy&#39;) replace,           --替换

       translate(&#39;wish1&#39;,&#39;1&#39;,&#39;y&#39;)translate,               --转换,对应一位(前面的位数大于等于后面的位数)
       translate(&#39;wish1&#39;,&#39;sh1&#39;,&#39;hy&#39;)translate1,

       concat(&#39;11&#39;,&#39;22&#39;) concat                     --连接


from dual;

这里写图片描述

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