基本
create table table1( id varchar(300) primary key, name varchar(200) not null); --新建表
insert into table1 (id,name) values ('aa','bb');--插入数据
update table1 set id = 'bb' where id='cc'; --更新数据
delete from table1 where id ='cc'; --删除数据
drop table table1; --删除表
alter table table1 rename to table2; --修改表名
insert into table1 (select * from table2);--表数据复制
create table table1 select * from table2 where 1>1; --复制表结构
create table table1 select * from table2; --复制表结构和数据
create table table1 as select id, name from table2 where 1>1; --复制指定字段
select id,name (case gender when 0 then '男' when 1 then ‘女’ end ) gender from table1 --条件查询
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 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;
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
分页查询
--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;
时间的处理
--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
---时间格式
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;
--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;
--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;
--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;
字符串函数
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;
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;
锁表
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--查看锁表进程SQL语句1：
select sess.sid,
sess.serial#,
lo.oracle_username,
lo.os_user_name,
ao.object_name,
lo.locked_mode
from v$locked_object lo,
dba_objects ao,
v$session sess
where ao.object_id = lo.object_id and lo.session_id = sess.sid;
--查看锁表进程SQL语句2：
select * from v$session t1, v$locked_object t2 where t1.sid = t2.SESSION_ID;
--杀掉锁表进程：
如有記錄則表示有lock，記錄下SID和serial# ，將記錄的ID替換下面的738,1429，即可解除LOCK
alter system kill session '738,1429';