??????? oracle，簡(jiǎn)單來(lái)說(shuō)就是數(shù)據(jù)庫(kù)，數(shù)據(jù)庫(kù) ，顧名思義，就是存放數(shù)據(jù)的容器！！

不知道oracle的我先科普一下吧~~~科普，科學(xué)普及簡(jiǎn)稱科普，又稱大眾科學(xué)或者普及科學(xué)，是指利用各種傳媒以淺顯的、讓公眾易于理解、接受和參與的方式向普通大眾介紹自然科學(xué)和社會(huì)科學(xué)知識(shí)、推廣科學(xué)技術(shù)的應(yīng)用、倡導(dǎo)科學(xué)方法、傳播科學(xué)思想、弘揚(yáng)科學(xué)精神的活動(dòng)。

??????? nice，科普完畢，接下來(lái)廢話不多說(shuō)了，直接上代碼案例，前人說(shuō)：腦子是個(gè)好東西，得用起來(lái)！！！后人補(bǔ)充到：古人說(shuō)的對(duì)！！！

select * from scott.emp; select eName from scott.emp; select rowid,ename from scott.emp where ename='SMITH'; select emp.*,rownum from scott.emp where rownum<11;--創(chuàng)建學(xué)員信息表 create table student ( stuNo char(6) not null, stuName varchar2(20) not null, stuAge number(3,0) not null, stuID number(18,0), stuSeat number(2,0) );insert into stuinfo(stuNo,stuname,stuAge,stuSeat)values('2','活動(dòng)',25,3) select * from stuinfo--查詢表的位置 select tablespace_name,table_name from user_tables where table_name=upper('stuinfo');--創(chuàng)建表空間 create tablespace test datafile 'D:\oracle\shujuku\test.ora' size 1000M; create user test identified by test default tablespace test quota 500M on users; grant all privileges to test;--查看表空間 select file_name,tablespace_name,bytes,autoextensible from dba_data_files where tablespace_name='test';select * from test.stuinfo;--提交事務(wù) commit; select * from scott.emp;--修改密碼 alter user system identified by 123;select * from scott.emp; --rowid偽列數(shù)據(jù)對(duì)象編號(hào) 文件編號(hào) 塊編號(hào) 行編號(hào) select e.*,rowid from scott.emp e; --rownum,從1開(kāi)始，大于1的東西查不出來(lái)，小于等于某個(gè)值可以查詢 select e.*,rownum from scott.emp e where rownum<=10; select * from scott.dept; insert into scott.dept(deptno,dname,loc)values('5','1111','dsds'); commit;delete from scott.dept where deptno='5' ;commit;----創(chuàng)建學(xué)員信息表 create table student ( stuNo number not null, stuName varchar2(20) not null, stuAge number(3,0) not null, stuSeat number(2,0) ); select * from studentinsert into student(stuNo,stuname,stuAge,stuSeat)values('1','張三',18,1); insert into student(stuNo,stuname,stuAge,stuSeat)values('2','李四',20,2); insert into student(stuNo,stuname,stuAge,stuSeat)values('3','王五',15,3); insert into student(stuNo,stuname,stuAge,stuSeat)values('4','張三',18,4); insert into student(stuNo,stuname,stuAge,stuSeat)values('5','張三',20,5);--事務(wù)的處理 --沒(méi)有添加進(jìn)去編號(hào)8 insert into student(stuNo,stuname,stuAge,stuSeat)values('6','王五1',12,6); insert into student(stuNo,stuname,stuAge,stuSeat)values('7','張三1',14,7); savepoint a; insert into student(stuNo,stuname,stuAge,stuSeat)values('8','張三',20,5); rollback to savepoint a; commit; select * from test.student;--選擇無(wú)重復(fù)的行distinct select distinct stuname from student;--選擇重復(fù)的行distinct(姓名和年齡) select distinct stuname ||stuage from student;/* 注釋的重要性 */ --別名 select distinct stuname "姓名" from student;--復(fù)制一個(gè)表 as后邊加一個(gè)select create table newstudent1 as select * from student; select * from newstudent1 ; --復(fù)制表的結(jié)構(gòu)（不包括數(shù)據(jù)） create table newstudent as select * from student where 1=2; select * from newstudent;--查詢表中的記錄數(shù) select count(1) from student;--查詢姓名和年齡中不存在重復(fù)的記錄 --大于等于是查詢重復(fù)的，小于是查詢不重復(fù)的 select stuname,stuage from student group by stuname,stuage having(count(stuname||stuage)<2); select stuname,stuage from student group by stuname,stuage having(count(stuname||stuage)>1); select stuname from student group by stuname having(count(stuname)<5);--查詢用戶數(shù)量大于10的 select * from user_all_tables a where a.num_rows>1;--添加列，刪除列 alter table student add(phone varchar2(20),emil varchar2(20)); alter table student drop(phone); select * from student;select * from stuinfo; select stuname from student group by stuname having(count(stuname)>1);/* oracle的日期函數(shù)last_day 意思是得到每月的最后一天,用這個(gè)函數(shù),我們可以得到各種不同的日期. 1:得到當(dāng)前月第一天與最后一天 */ select to_char(trunc(sysdate,'MONTH'),'yyyymmdd')firstday , to_char(last_day(trunc(sysdate,'MONTH')),'yyyymmdd') lastdayfrom dual;--2:得到上月第一天與上月最后一天 SELECT to_char( last_day(add_months(SYSDATE, -2)) + 1 ,'yyyymmdd') firstday ,to_char(last_day(add_months(SYSDATE, -1)),'yyyymmdd') lastday FROM dual; --3:得到上上個(gè)月第一天與上上個(gè)月最后一天 SELECT to_char( last_day(add_months(SYSDATE, -3)) + 1 ,'yyyymmdd') firstday ,to_char(last_day(add_months(SYSDATE, -2)),'yyyymmdd')lastday FROM dual; --4:得到下個(gè)月第一天與下個(gè)月最后一天 SELECT to_char( last_day(add_months(SYSDATE, 0)) + 1 ,'yyyymmdd') firstday ,to_char(last_day(add_months(SYSDATE, 1)),'yyyymmdd')lastday FROM dual;
?????? nice,有的人可能之前沒(méi)學(xué)過(guò)數(shù)據(jù)庫(kù)，比如說(shuō)my sql ,sql server 等等，直接上來(lái)就是oracle，所以，推薦一部視頻，即使你沒(méi)有學(xué)過(guò)sql server什么的，或者學(xué)過(guò)沒(méi)深入理解的，那么，請(qǐng)點(diǎn)擊 這里，?密碼: 3ydr，一共46節(jié)課，足足夠你學(xué)會(huì)oracle了，拿走不謝！！！

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