[oracle@aa ~]$ rlwrap  sqlplus                     <----登录oracle      

SQL*Plus: Release 10.2.0.1.0 - Production on Fri Jun 10 18:44:06 2011

Copyright (c) 1982, 2005, Oracle.  All rights reserved.

Enter user-name: scott       <-----用户名
Enter password:              <-----密码

Connected to:
Oracle Database 10g Enterprise Edition Release 10.2.0.1.0 - Production
With the Partitioning, OLAP and Data Mining options

[oracle@aa db_1]$ vim  /u01/app/oracle/product/10.2/db_1/sqlplus/admin/glogin.sql
define _editor=vi      用pl/sql的时候ed编辑
set serveroutput on   用pl/sql的时候显示结果

select的语法
SELECT    *|{[DISTINCT] column|expression [alias],...}
FROM      table
[WHERE    condition(s)]
[ORDER BY {column, expr, alias} [ASC|DESC]];

SQL> set linesize 200           <-----修改每行的长度

SQL> select ename,sal,comm from emp;

ENAME             SAL       COMM
---------- ---------- ----------
SMITH             800
ALLEN            1600        300
WARD             1250        500
JONES            2975
MARTIN           1250       1400
BLAKE            2850               <---- 空值，不是0，未知或者无效的值               
CLARK            2450
SCOTT            3000
KING             5000
TURNER           1500          0
ADAMS            1100

ENAME             SAL       COMM
---------- ---------- ----------
JAMES             950
FORD             3000
MILLER           1300

14 rows selected.

SQL> select ename,sal,sal*comm from emp;    <----有空值在的表达式都是空值

ENAME             SAL   SAL*COMM
---------- ---------- ----------
SMITH             800
ALLEN            1600     480000
WARD             1250     625000
JONES            2975
MARTIN           1250    1750000
BLAKE            2850
CLARK            2450
SCOTT            3000
KING             5000
TURNER           1500          0
ADAMS            1100

ENAME             SAL   SAL*COMM
---------- ---------- ----------
JAMES             950
FORD             3000
MILLER           1300

14 rows selected.


SQL> select ename||sal as "employees's salary" from emp;   <---"    "保持双引号的大小写和空格

employees's salary
--------------------------------------------------
SMITH800
ALLEN1600
WARD1250
JONES2975
MARTIN1250
BLAKE2850
CLARK2450
SCOTT3000
KING5000
TURNER1500
ADAMS1100

employees's salary
--------------------------------------------------
JAMES950
FORD3000
MILLER1300

14 rows selected.

SQL> select ename||' is a '||job as "Employes Details" from emp;   <-- ' is a ' 必须用单引号，字符串和日期只能用单引号括起来

Employes Details
-------------------------
SMITH is a CLERK
ALLEN is a SALESMAN
WARD is a SALESMAN
JONES is a MANAGER
MARTIN is a SALESMAN
BLAKE is a MANAGER
CLARK is a MANAGER
SCOTT is a ANALYST
KING is a PRESIDENT
TURNER is a SALESMAN
ADAMS is a CLERK

Employes Details
-------------------------
JAMES is a CLERK
FORD is a ANALYST
MILLER is a CLERK

14 rows selected.


SQL> select distinct deptno from emp;   <----distinct是关键字，去重复的行 （在语法的解释里，关键字是大写的。）

    DEPTNO
----------
        30
        20
        10

字符和日期
字符和日期要包含在单引号中。
字符大小写敏感，日期格式敏感。
默认的日期格式是 DD-MON-RR。

 
SQL> select ename,mgr from emp where mgr is null;                   <---找出MGR是空值的人，null不能比较

ENAME             MGR
---------- ----------
KING


SQL> select ename,sal,deptno from emp  where deptno=10  order by sal desc;   <---从多到少    asc 升序，可以不写  desc  降序

ENAME             SAL     DEPTNO
---------- ---------- ----------
KING             5000         10
CLARK            2450         10
MILLER           1300         10


SQL> select deptno,trim(1 from deptno) from emp where deptno=10;

    DEPTNO TRIM(1FROMDEPTNO)
---------- ----------------------------------------
        10 0
        10 0
        10 0

SQL> select job,trim('C' from job) from emp where job='CLERK';

JOB       TRIM('C'F
--------- ---------
CLERK     LERK
CLERK     LERK
CLERK     LERK
CLERK     LERK

＊＊＊＊＊   只能去除首尾的字母？


SQL> select round(46.937,2),round(46.937,1),round(46.937,0),round(46.937,-1) from dual;   dual是一个伪表，用来测试函数和表达式

ROUND(46.937,2) ROUND(46.937,1) ROUND(46.937,0) ROUND(46.937,-1)
--------------- --------------- --------------- ----------------
          46.94            46.9              47               50

 


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  远程登录。
180------100
客户端          服务端

服务端必须有一个帐户，并且有连接的权限，开了监听
客户端配置了监听

sqlplus ly/ly@o100

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