oracle常用sql语句
2017-08-08 16:43
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1)基本
2)数学函数
3)rownum
4)分页
-不包含排序
-包含排序
5)时间处理
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6)字符函数
--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 4000 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,'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;
months_between select months_between(to_date('03-31-2014','MM-DD-YYYY'),to_date('12-31-2013','MM-DD-YYYY')) "MONTHS" FROM DUAL;
next_day select sysdate today, next_day(sysdate,6) nextweek from dual;
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;
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, --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;
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