三、字符比较： 1、char和varchar 2、char和nchar，varchar和nvarchar

在informix中有如下几种对字符串操作的类型： char(character),varchar,nchar,nvarchar,lvarchar,text 在ORACLE中有如下几种对字符串操作的类型： char(character),varchar(varchar2),nchar,nvarchar2,long,long raw及LOB类型

一、基本概念： 1、字符存储单位 2、char:定长的字符串类型 3、varchar：描述变长字符串

二、INFORMIX ORACLES数据类型对应长度及比较 informix Oracle 范围 默认长度 作为数据存储 变量 char 1~32767 1 1~2000 1~32767 varchar 1~255 1 1~4000 1~

四、oracle里的数据类型: 1、char,character,varchar,varchar2,nchar,nvarchar2的共同特点： 当插入空字符串时，则都会被转变为null

五、informix里的字符: 1、lvarchar在9.4版本之后才可以用带指定长度的方式，如lvarchar(3000)，不带长度则默认是2048字节，最大长度是32,739字节。 所以对于9.4之前的版本，不能用带长度的表达式，数据库会报语法错误。

六、oracle和informix表的限制 1、在informix的一个表中对以上字符串类型定义的总长度不能超过32767(不包括对大字段处理的text类型) 但是遇到varchar与nvarchar会再减1(为该列设置索引会留一位)，而遇到lvarchar则需要减3。 2、oracle限制的每个表的列的总数不能超过1000(此处没有测试),然后每个列的长度由其数据类型决定。 每个索引的最大列数 32

七、行迁移与行链接 当一行的数据过长而不能插入一个单个数据块中时，可能发生两种事情：行链接(row chaining)或行迁移(row migration)。

八、ORACLE－在设计数据库时如何选择正确的数据类型

More power than all the success slogans ever penned by human hand is the realization for every man that he has but one boss. That boss is the man - he - himself.

Judaism to me, as badly as I practiced it, what I've always loved about it was its total embrace of complexity, its admission of unknowability.

It doesn't matter what people think of me. I've lived my life.

I've been making shoes my whole life.

Don't feel guilty for doing what's best for you.

As a kid, I'd get up at 3 in the morning during school vacations to help my father on his bakery-truck route. He didn't get a vacation from that schedule.

Selling is something we do for our clients - not to our clients.

Collecting is the sort of thing that creeps up on you.

The independence of all political and other bother is a happiness.

I have a very solo career. I only write with people that I really adore.

I stand with the majority of Americans who believe that women will make the right choice for their families and everyone will win.

I am what I am, but I'm not a thief. And I'm not scandalous.

You just hope that you will get the opportunity to do what you love and pay your bills, and that is being a success as an actor.

No matter how loud the stadium is, once you're on that field and that offense walks up to the line, it's silent. You can only hear the guys on the field. It's amazing how much concentration you can have when it's required and how powerful your mind is to give it to you.

When I drew Captain America in 'The Ultimates,' I hated my Cap, even though some people are like, 'Man, your Cap's cool!' and they made statues out of it.

I've loved the opportunity to learn about the fashion world and appreciate it as an art form, and I look forward to my continued education, but I never want it to take over my acting.

I do not pretend to know precisely what is on foot there; but I think it pretty evident that there is a very free communication between that country and this body, and unless I am greatly mistaken, I see the dwarfish medium by which that communication is kept up.

I actually have a stash of wigs for Halloween. But only for that. Not to play dress-up.

Yet through history gays have always dominated religious life and churches.

Black history is part of American history and it should be treated as such.

I had been stockpiling Gospel songs for other artists, and had planned to submit them to Gospel artists.

It's always a surprise! This business is always an adventure.

We are by nature observers, and thereby learners. That is our permanent state.

I love my fans, so when I get the chance to interact with them, it's beautiful.