Linux系统中数据库启动和关闭&Basic SQL-Unix
第一步：使用oracle用户登录第二步：在oracle用户下输入sqlplus /nolog
第三步：如需使用管理员权限，则输入connect /as sysdba
第四步：启动和关闭
startup
startup nomount #只启动实例
startup mount #打开控制文件
startup open #打开数据文件和重做日志
shutdown
shutdown normal #不接受新的连接，需要等待所有的用户断开连接
shutdown immediate #回滚未结束的事务关闭数据库
shutdown transactional #等用户结束事务关闭数据库
shutdown abort #直接关闭数据库
第五步：如果是启动服务，要开启监听
退出sqlplus模式输入lsnrctl start
$ sqlplus /nolog
SQL*Plus:> Copyright (c) 1982, 2009, Oracle.All rights reserved.
SQL> conn /as sysdba
Connected to an> SQL> startup
ORACLE instance started.
Total System Global Area551165952 bytes
Fixed>
Variable> Database Buffers 171966464 bytes
Redo Buffers 3690496 bytes
Database mounted.
Database opened.
SQL>
解锁scott用户：
SQL>>
User> SQL> commit;
Commit complete.
SQL> conn scott/tiger
ERROR:
ORA-28001: the password has expired
Changing password for scott
New password:
Retype new password:
Password changed
Connected.
显示当前用户：
SQL> show user
USER is "SCOTT"
设置SQL*Plus的环境变量：linesize和pagesize
SQL> set linesize 300
SQL> set pagesize 3000
计算一个查询花费的时间：
SQL> set timing on
SQL> select * from dept;
DEPTNO DNAME LOC
---------- -------------- -------------
10 ACCOUNTING NEW YORK
20 RESEARCH DALLAS
30 SALES CHICAGO
40 OPERATIONS BOSTON
Elapsed: 00:00:00.07
SQL>
emp,dept,salgrade表结构如下：
DEPT表：
EMP表：
salgrade表：
查询emp表中所有人的姓名：
SQL> select ename from emp;
ENAME
----------
SMITH
ALLEN
WARD
JONES
MARTIN
BLAKE
CLARK
SCOTT
KING
TURNER
ADAMS
JAMES
FORD
MILLER
14 rows selected.
SQL>
把查询结果中ename改为中文“姓名”：
SQL> select ename 姓名 from emp;
查询emp表中不重复的部门：
SQL> select distinct deptno from emp;
DEPTNO
----------
30
20
10
SQL>
查询emp表中工资大于2k的员工：
SQL> select ename,sal from emp where sal>2000;
ENAME SAL
---------- ----------
JONES 2975
BLAKE 2850
CLARK 2450
SCOTT 3000
KING 5000
FORD 3000
6 rows selected.
SQL>
查询emp表中工资3k到3k的员工：
SQL> select ename,sal from emp where sal between 2000 and 3000;
ENAME SAL
---------- ----------
JONES 2975
BLAKE 2850
CLARK 2450
SCOTT 3000
FORD 3000
SQL>
查询emp表中，ename列以A开头的员工:
SQL> select ename from emp where ename like 'A%';
ENAME
----------
ALLEN
ADAMS
SQL>
查询emp表中，ename列含有A的员工:
SQL> select ename from emp where ename like '%A%';
ENAME
----------
ALLEN
WARD
MARTIN
BLAKE
CLARK
ADAMS
JAMES
7 rows selected.
SQL>
查询没有员工的部门：
SQL> select * from dept where deptno in (select deptno from emp group by deptno having count(*)
查询有员工的部门：
SQL> select * from dept where deptno in (select deptno from emp group by deptno having count(*)>1);
DEPTNO DNAME LOC
---------- -------------- -------------
30 SALES CHICAGO
20 RESEARCH DALLAS
10 ACCOUNTING NEW YORK
SQL>
查询emp表中姓名和工资额，按照工资降序排列：
SQL> select ename,sal from emp order by sal desc;
ENAME SAL
---------- ----------
KING 5000
FORD 3000
SCOTT 3000
JONES 2975
BLAKE 2850
CLARK 2450
ALLEN 1600
TURNER 1500
MILLER 1300
WARD 1250
MARTIN 1250
ADAMS 1100
JAMES 950
SMITH 800
14 rows selected.
SQL>
查询emp表中补贴为null的员工：
SQL> select ename,comm from emp where comm is null;
ENAME COMM
---------- ----------
SMITH
JONES
BLAKE
CLARK
SCOTT
KING
ADAMS
JAMES
FORD
MILLER
10 rows selected.
SQL>
使用to_char函数查询1981年入职的员工：
SQL> select ename,hiredate from emp where to_char(hiredate,'yyyy')='1981';
ENAME HIREDATE
---------- ---------
ALLEN 20-FEB-81
WARD 22-FEB-81
JONES 02-APR-81
MARTIN 28-SEP-81
BLAKE 01-MAY-81
CLARK 09-JUN-81
KING 17-NOV-81
TURNER 08-SEP-81
JAMES 03-DEC-81
FORD 03-DEC-81
10 rows selected.
SQL>
使用nvl函数查询每个人每个月的总收入，如果补贴为null，则视其为0：
SQL> select ename,sal+nvl(comm,0),comm from emp;
ENAME SAL+NVL(COMM,0) COMM
---------- --------------- ----------
SMITH 800
ALLEN 1900 300
WARD 1750 500
JONES 2975
MARTIN 2650 1400
BLAKE 2850
CLARK 2450
SCOTT 3000
KING 5000
TURNER 1500 0
ADAMS 1100
ENAME SAL+NVL(COMM,0) COMM
---------- --------------- ----------
JAMES 950
FORD 3000
MILLER 1300
14 rows selected.
SQL>
查询emp表中哪些员工补贴比工资还高：
SQL> select ename,sal,comm from emp where comm>sal;
ENAME SAL COMM
---------- ---------- ----------
MARTIN 1250 1400
SQL>
查询每个部门的最高工资：
SQL> select deptno,max(sal) from emp group by deptno;
DEPTNO MAX(SAL)
---------- ----------
30 2850
20 3000
10 5000
SQL>
查询每个部门是那个员工获得了部门的最高工资：
SQL> select e1.ename,e1.sal,e1.deptno from emp e1,(select deptno,max(sal)最大值 from emp group by deptno) e2 where e1.deptno=e2.deptno and e1.sal=e2.最大值;
ENAME SAL DEPTNO
---------- ---------- ----------
BLAKE 2850 30
SCOTT 3000 20
KING 5000 10
FORD 3000 20
SQL>
查询10号部门和20号部门平均工资的差异:
SQL> select (select avg(sal) from emp where deptno=10)-(select avg(sal) from emp where deptno=20) distance from dual;
DISTANCE
----------
741.666667
SQL>
查询emp表每个员工和最高工资之间的差距：
SQL> select ename,(select max(sal) from emp)-sal distan from emp;
ENAME DISTAN
---------- ----------
SMITH 4200
ALLEN 3400
WARD 3750
JONES 2025
MARTIN 3750
BLAKE 2150
CLARK 2550
SCOTT 2000
KING 0
TURNER 3500
ADAMS 3900
ENAME DISTAN
---------- ----------
JAMES 4050
FORD 2000
MILLER 3700
14 rows selected.
SQL>
查询emp表中工资超过平均工资的员工：
SQL> select ename,sal from emp where sal>(select avg(sal) fromemp);
ENAME SAL
---------- ----------
JONES 2975
BLAKE 2850
CLARK 2450
SCOTT 3000
KING 5000
FORD 3000
6 rows selected.
SQL>
查询每个部门中工资超过平均工资的员工：
SQL> select deptno,ename,sal from emp where sal>(select avg(sal) fromemp);
DEPTNO ENAME SAL
---------- ---------- ----------
20 JONES 2975
30 BLAKE 2850
10 CLARK 2450
20 SCOTT 3000
10 KING 5000
20 FORD 3000
6 rows selected.
SQL>
列出所有部门的详细信息和部门人数：
SQL> select a.*,(select count(*) from emp where deptno=a.deptno) total from dept a;
DEPTNO DNAME LOC TOTAL
---------- -------------- ------------- ----------
10 ACCOUNTING NEW YORK 3
20 RESEARCH DALLAS 5
30 SALES CHICAGO 6
40 OPERATIONS BOSTON 0
SQL>
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