150103 Pro Oracle SQL

RDBMS=relational database management systems
ANSI=American National Standards Institute
Oracle Call Interface (OCI). Oracle调用界面
The bottom
line is that the tool you use doesn’t matter; the native interface is the same for all.


here are actually two files that SQL*Plus reads by default each time you start it. The first is glogin.sql and it can
be found in the directory $ORACLE_HOME/sqlplus/admin. If this file is found, it is read and the statements it contains
are executed. This allows you to store the SQL*Plus commands and SQL statements that customize your experience
across SQL*Plus sessions.
After reading glogin.sql, SQL*Plus looks for the login.sql file. This file must exist in either the directory
from which SQL*Plus was started or in a directory included in the path to which the environment variable SQLPATH
points. Any commands in login.sql will take precedence over those in glogin.sql.

Win8 安装64位Oracle11g R2

I installed the oracle 11g r2 today... oui  Oracle Universal Installer

2015.1.11

I installed 11g r2, and sql developer, now I will formally start my learning trip for oracle sql!!!!    :)

alter session set nLS_date_language='AMERICAN';

ALTER SESSION SET NLS_DATE_FORMAT='YYYY"年" MM "月" DD"日"';

当算数表达式包含ｎｕｌｌ时显示结果也是ｎｕｌｌ。

ｎｖｌ２（ｃｏｌｕｍｎ，不为空返回值，为空返回值）

select '''' from dual;　　－－　返回　　‘

select concat(concat(ename,'''s salary is'),sal) from emp;－－－SMITH's salary is800