oracle train（一）

连接    connect conn
LM-? mT7X{J0connect username/password as sysdba
a ikM'y,K0y/f0普通用户51Testing软件测试网7W8H9pRvW+h/?
scott tiger51Testing软件测试网
QDr&_7MSbC
hr   hr51Testing软件测试网*L+iFQ zI7?.U
管理员
'l
iKN$L e9]0sys change_on_install
4^!G^v,U0system manager查共有多少表： tabs        user_table显示用户：
"C(gd;Q b3^4L @0show user;51Testing软件测试网f6G(t hJr;w9w7QUo$I
管理员解锁用户51Testing软件测试网 n$~^P(T6p.u
alert user username (hr) account unlock51Testing软件测试网@|FbY~9?G D[ P
alert user username (hr) identified by hr给一个列取别名：
4x"i
NY`#a;~0column_name as "alias name" (两个别名的单词一定要加“”)51Testing软件测试网~HI,g%juM1p+T

http://localhost:7778/isqlplus51Testing软件测试网2rZh9X/{1f JWW
连接两个字段：
j,b{\:hV#Z o0select last_name||job_id as "Employees" from employees;51Testing软件测试网J$T9mB,Xl \*Tv
插入字符串：51Testing软件测试网!s9d,_|1w*~G
select last_name||'is a '||job_id as "Employees details" from employees;
!Np6h/kW_n0匹配语句：select first_name from employees where first_name like '__a%';

tUP!_*D@*G0转移字符：first_name like '%\%ab' escaple '\'  (查找以%ab结尾的词)

select first_name manager_id from employees where manager_id is  Null;51Testing软件测试网_E8IT2dIlD.f

排序（默认为升序）select last_name,job_id,department_id,hire_date from employees order by hire_date desc;51Testing软件测试网#r4fbj b9s

/^9f
S%`VA;w0select department_id,last_name,salary   from employees order by department_id,salary desc;51Testing软件测试网A,kGo9zuk#dS

a;f:S:cY,i/w0函数：把大写字母变成小写：lower()  51Testing软件测试网W#YEbu3zwr W

把小写字母变成大写： upper()51Testing软件测试网VMF*X/tm+Q

把第一个字母变大写其余的小写： initcap(asdWJ) :Asdwj

concat(hello, world) :helloworld

1fhP2rZ0substr(helloworld  3,6):llow

!A7Hc:Q9\#o u0O0length(last_name)

ke'_a2Ikz0instr('helloworld' 'w') :651Testing软件测试网3Hd)cU&Q/x9w

lpad(salary,10,'*'):*******100

rpad(salary,10,'*') :100*******51Testing软件测试网9V)d0ijda`+]Q

select round(45.936,-1) from dual; 50
_6Xv&q.H:jy_d0select round(45.936,-2) from dual; 0
,T~ U/o G2qc0select round(45.936,0) from dual;   46
&z/aOX L^s"[
K_ e'X0select round(45.936,1) from dual;    45.951Testing软件测试网/KL2_g*^w.Y
select round(45.936,2) from dual;     45.94

d,q4|"@:E%[0
Kz lwA)Y~3H051Testing软件测试网'O/eYo4z} C