Pramary
oracle_primary用法_概述及解释说明
oracle primary用法概述及解释说明1. 引言1.1 概述在关系型数据库中，Primary Key（主键）是一种重要的数据库约束，用于唯一标识一个表中的每一行数据。
它是数据库设计中非常重要的概念之一，对于保障数据完整性和提高查询效率都具有很大作用。
本文将详细介绍Oracle数据库中Primary Key的用法及其相关解释说明。
1.2 文章结构本文由以下几个部分组成。
首先是引言部分，对文章进行概述，并介绍文章的结构。
接下来是Oracle Primary用法部分, 介绍了Primary Key的基本定义、作用以及如何定义和使用Primary Key。
然后是Primary Key的特点和限制部分, 包括唯一性约束、非空约束以及自动递增特性等。
随后是如何选择和设计Primary Key部分, 讨论根据业务需求选择合适的Primary Key类型、设计复合主键时需要考虑的因素以及索引对Primary Key性能的影响等方面内容。
最后是结论部分，总结了Primary Key在数据库设计中的重要性与应用价值，并给出了正确使用Primary Key提高数据完整性和查询效率的建议，并展望了未来Database设计发展趋势。
1.3 目的本文旨在全面介绍Oracle Primary Key的用法，帮助读者深入了解Primary Key 的概念、作用和限制，以及如何正确选择和设计Primary Key。
通过本文的阅读，读者将能够更好地理解Primary Key在数据库设计中的重要性，并能够合理运用它来提高数据库的性能和数据完整性。
此外，本文还对未来Database设计发展趋势进行了展望，为读者提供思考与探索的方向。
2. Oracle Primary用法：2.1 什么是Primary KeyPrimary Key（主键）是数据库表中的一列或一组列，其具有唯一性和非空性的特点。
每个数据库表都应该有一个Primary Key，它用于唯一标识表中的每行数据。
BIOS的基本单词
Execute Disable Bit：执行取消位，病毒防护技术。cpu thermal throttling：CPU热量控制，CPU散热技术。 throttling：节流。 APIC：高级可编程中断控制器。
MPS Version Control For OS：系统支持的MPS的版本号。assign：分配。IRQ：中断号。Assign IRQ For VGA[Enabled] ：为视频图形适配器分配IRQ 。unused：闲着的。chipset：芯片。
frequency：频率。FSB：前端总线。 FSB Frequency：外频设定，CPU外频设定。SPD ：电涌保护器
status[?steit?s ：身份, 地位，情形, 状况。Boot Up NumLock Status： 开机时的软盘驱动器搜索 该项为选择在系统启动时是否检测软驱 可用选项Enabled 。Option：选择。security[si?kju?riti]：安全。OS：操作系统。select[si?lekt]：选择。logo：标签。small：少量的。show：显示。Boot Sequence[?si:kw?ns]：启动顺序。 threading[?θredi?]： hyper： 宣传人员。hyper-threading ：超线程技术。function:功能。typematic:重复击键的,字元输入速率.Typematic Delay(Msec):延迟。Typematic Rate：字元输入速ce： 顺序, 连续。speed：速率。tech：技术。delay：延迟。prior：优先的; 在前的; 较早的。thermal：热的, 热量的, 由热造成的。delay prior to thermal：发热前延迟，延迟之前热。
primary造句
primary造句1、He made no mention of primary colors.他没有提到基色。
2、Science didactics in primary schools in one of these subjects.小学理科教授法系其中的一科。
3、The pool identified as the reclamation storage pool must bea primary sequential storage pool.回收存储池的池的类型必须是主顺序存储池。
4、A natural preservative CP-F was prepared by using hesperidinas primary raw material.用桔皮提取物橙皮甙为主要原料制备了天然果蔬护色保鲜剂CP - F。
5、Psyllium offers benefits in patients with irritable bowel syndromein primary care.欧车前在肠易激综合征患者的初级保健中疗效最佳。
6、Primary election has been running for months.初选已经开始了几个月。
7、It comes in bright primary colours that kids will love.它的颜色都是孩子们喜爱的亮丽原色。
8、Shorter light incubation time always causes high primary production and assimilation number.短的曝光时间往往带来高的初级生产力和同化系数。
9、Parody constructs one of the primary features of postmodernist fiction.戏仿是后现代主义小说的一个主要特征。
六级常考近义词辨析
1．transaction ／transition ／transformation ／transmissiontransaction："交易，事务，事项"；"办理，执行"transition："过渡，过渡时期"transformation："改变，改观，改造"transmission："传送，传递，传达，传导"典型考题分析：［例1］The ____ from childhood to adulthood is always a critical time for every-body．（2001．6）A）conversion B）transitionC）turnover D）transformation［题解］题意是：对每个人而言，从儿童到成人的过渡是一个关键时期。
选项conversion意思是"变换，转变"，而turnover意思是"成交量，营业额；人员调整"。
根据题意，答案为B）。
［例2］Cultural ____ indicates that human beings hand their language down from one generation toanother．（2001．1）A）translation B）transitionC）transmission D）transaction［题解］题意是：文化继承是指人类将其语言代代相传。
根据题意，答案为C）。
［例3］He attends to the ____of important business himself．（1998．6）A）transaction B）transitionC）transmission D）transformation［题解］题意是：他亲自参与重要商业贸易的处理。
初级教育的英语
初级教育的英语一、单词1. primary- 英语释义：first in order of time or development; leading to or being an early stage of a moreplex form.- 用法：可作形容词，修饰名词。
例如“primary education”（初级教育），“primary school”（小学）。
- 双语例句：Primary education is the foundation of a person's learning journey.（初级教育是一个人学习旅程的基础。
）2. elementary- 英语释义：relating to the basic elements or principles; simple and basic.- 用法：形容词，用于描述事物的基础、简单性质。
如“elementary school”（小学，与primary school同义）。
- 双语例句：Elementary education should focus on cultivating children's basic skills.（初级教育应该着重培养孩子的基本技能。
）3. basic- 英语释义：forming an essential foundation or starting - point; fundamental.- 用法：形容词，常用来修饰各类名词表示基本的。
例如“basic knowledge in primary education”（初级教育中的基础知识）。
- 双语例句：Basic reading and writing skills are taught in primary education.（初级教育中教授基本的读写技能。
）4. foundation- 英语释义：the lowest load - bearing part of a building, typically below ground level; an underlying basis or principle.- 用法：可作名词，在与初级教育相关表达中，常表示基础、根基。
英文作文 primary
英文作文 primary下载温馨提示:该文档是我店铺精心编制而成，希望大家下载以后，能够帮助大家解决实际的问题。
文档下载后可定制随意修改，请根据实际需要进行相应的调整和使用，谢谢!并且，本店铺为大家提供各种各样类型的实用资料，如教育随笔、日记赏析、句子摘抄、古诗大全、经典美文、话题作文、工作总结、词语解析、文案摘录、其他资料等等，如想了解不同资料格式和写法，敬请关注!Download tips: This document is carefully compiled by theeditor. I hope that after you download them,they can help yousolve practical problems. The document can be customized andmodified after downloading,please adjust and use it according toactual needs, thank you!In addition, our shop provides you with various types ofpractical materials,such as educational essays, diaryappreciation,sentence excerpts,ancient poems,classic articles,topic composition,work summary,word parsing,copyexcerpts,other materials and so on,want to know different data formats andwriting methods,please pay attention!I woke up this morning feeling absolutely exhausted.It's like I didn't even sleep at all. I must have tossed and turned all night.After dragging myself out of bed, I stumbled into the kitchen to make some coffee. I can't function without my morning caffeine fix. As I waited for the coffee to brew, I stared out the window and watched the sun slowly rise.Once I had my coffee in hand, I sat down at the kitchen table and tried to wake myself up. I scrolled through my phone, mindlessly checking social media and the news. It's amazing how much time can disappear when you're lost in the endless scroll.Eventually, I realized that I was going to be late if I didn't get moving. I quickly got ready for the day, throwing on some clothes and grabbing my bag on the way out the door. I really need to work on my time managementskills.As I rushed to catch the bus, I couldn't help but feel like I was forgetting something. Did I leave the stove on? Did I forget to lock the front door? I guess I'll just have to worry about it all day.Finally on the bus, I found a seat and tried to relax. But of course, the person next to me decided to strike up a conversation. I'm really not a morning person, and small talk is the last thing I want to deal with right now.At last, I arrived at work and dove headfirst into the day's tasks. The morning seemed to drag on forever, and I couldn't shake the feeling that today was going to be a long one. But hey, at least it's Friday, right?。
UNIQUE和PRIMARY约束的区别
UNIQUE和PRIMARY约束的区别
定义了UNIQUE约束的字段中不能包含重复值，可以为⼀个或多个字段定义UNIQUE约束,因此，UNIQUE即可以在字段级也可以在表级定义，在UNIQUE约束的字段上可以包含空值. ORACLE⾃动会为具有PRIMARY KEY约束的字段(主码字段)建⽴⼀个唯⼀索引和⼀个NOT NULL约束,定义PRIMARY KEY约束时可以为它的索引； UNIQUED 可空，可以在⼀个表⾥的⼀个或多个字段定义；
PRIMARY KEY不可空不可重复，在⼀个表⾥可以定义联合主键；简单的说, primary key = unique + not null
unique就是唯⼀,当你需要限定你的某个表字段每个值都唯⼀,没有重复值时使⽤. ⽐如说,如果你有⼀个person_Info表,并且表中有个⾝份证的column,那么你就可以指定该字段unique.
从技术的⾓度来看，Primary Key和Unique Key有很多相似之处。
但还是有以下异同：
相同:它们都属于实体完整性约束.
不同点:
(1) 唯⼀性约束所在的列允许空值，但是主键约束所在的列不允许空值。
(2) 可以把唯⼀性约束放在⼀个或者多个列上，这些列或列的组合必须有唯⼀的。
但是，唯⼀性约束所在的列并不是表的主键列。
(3) 唯⼀性约束强制在指定的列上创建⼀个唯⼀性索引。
在默认情况下，创建唯⼀性的⾮聚簇索引，但是，也可以指定所创建的索引是聚簇索引。
(4)建⽴主键的⽬的是让外键来引⽤.
(5)⼀个表最多只有⼀个主键，但可以有很多唯⼀键。
primary词根
Primary: Exploring the Essence of the Word RootIntroductionThe importance of word roots cannot be underestimated in language. These foundational units form the basis of many words and help us understand their meanings. One such word root is “primary,” which originates from the Latin word “primus,” meaning “first.” In this article, we will delve into the concept of “primary” and explore its various applications and implications across different domains.The Fundamentals of “Primary”DefinitionAt its cor e, “primary” refers to something that is first, earliest, or most essential in nature. It signifies the initial stage or the main component of a system or process. “Primary” denotes the primary focus, the principal factor, or the leading aspect in a particular context.EtymologyThe word root “primary” found its roots in the Latin language. The Latin term “primarius” gave birth to the English word “primary” as we know it today. The concept of the first or the foremost has been central to human civilization since ancient times, and this concept transcended into various languages, including English.The Different Facets of “Primary”Primary Education: Laying the FoundationPrimary education plays a pivotal role in a child’s development. It serves as the initial phase of formal education, where basic skills, knowledge, and values are imparted. The primary level sets the foundation for a lifelong journey of learning, fostering intellectual,social, and emotional growth. It equips children with essential skills and prepares them for higher levels of education.Importance of Primary Education:1.Acquisition of Fundamental Skills: Primary education focuses onteaching fundamental skills, such as reading, writing, andarithmetic, which are crucial for future academic success.2.Building Socialization and Communication Skills: Throughinteractions with peers, primary education facilitates thedevelopment of communication skills, teamwork, and socialization.3.Instilling Values and Ethics: Primary education introduceschildren to moral values, ethics, and citizenship, shaping theircharacter and encouraging responsible behavior.Primary Sector: The Backbone of the EconomyThe primary sector, also known as the agricultural sector, forms the foundation of any economy. It encompasses activities related to the extraction and production of natural resources, including farming, mining, forestry, and fishing. The primary sector contributes to the initial stage of the production process, providing raw materials for other industries.Key Aspects of the Primary Sector:1.Agricultural Development: Agriculture is a primary sector activitythat involves the cultivation of crops, animal husbandry, andrelated practices. It ensures food security, provides employmentopportunities, and contributes to the overall economic growth.2.Extractive Industries: The primary sector includes extractiveindustries such as mining and quarrying. These activities involve the extraction of minerals, fossil fuels, and other valuableresources from the earth’s crust.3.Sustainable Practices: As environmental concerns grow, the primarysector is increasingly focusing on sustainable practices. It aims to strike a balance between economic development and environmental conservation.Primary Sources: Authentic and Reliable InformationIn research and academia, primary sources hold immense significance. These sources are original materials that provide firsthand or direct evidence of a particular event, phenomenon, or subject. Primary sources offer credibility and reliability, enabling researchers to form accurate interpretations and draw informed conclusions.Examples of Primary Sources:1.Original Research Articles: Research papers published by scholarsin academic journals are primary sources that present originalfindings and methodologies.2.Historical Documents: Diaries, letters, official records, andmanuscripts from specific time periods serve as primary sourcesfor understanding historical events and perspectives.3.Personal Interviews: Conducting interviews with individuals whowitnessed or participated in significant events provides firsthand accounts, making them primary sources.Primary Colors: The Basis of Visual PerceptionPrimary colors are fundamental hues that cannot be created by mixing other colors. They are the building blocks for creating various shades, tints, and tones. In traditional color theory, red, blue, and yellow are considered primary colors. These primary colors can be mixed together to form secondary and tertiary colors, offering endless possibilities for artistic expression.Significance of Primary Colors:1.Color Mixing: Primary colors form the basis of color mixingtechniques. By combining primary colors in different proportions, an artist can achieve a wide range of colors.2.Visual Perception: Primary colors are essential for understandingthe principles of vision and color perception. They demonstratethe additive and subtractive color models.3.Symbolism: In art, primary colors often carry symbolic meanings.Red may represent passion, blue can symbolize calmness, and yellow is associated with joy and happiness.ConclusionThe word root “primary” encompasses a myriad of meanings and applications across various domains. From primary education to the primary sector, from primary sources to primary colors, the concept of “primary” highlights the fundamental, essential, and first stages of a process or system. Understanding the essence of this word root enhances our grasp of language and our interpretation of the world around us. So, let us embrace and explore the primary aspects of life with zest and curiosity.。
primary
primaryThe Importance of Primary Education in Shaping the FutureIn the intricate tapestry of human development, primary education stands as a fundamental thread, weaving together the aspirations of individuals with the progress of societies. It is a cornerstone upon which the edifice of knowledge, character, and societal well-being rests. This essay delves into the paramount significance of primary education, exploring how it serves as a catalyst for personal growth, societal advancement, and global interconnectedness.A Launchpad for Lifelong LearningPrimary education, the first formal phase of learning, serves as an indispensable launchpad for children's intellectual and emotional journey. It introduces students to the foundational skills of literacy, numeracy, and critical thinking, laying the groundwork for more advanced studies later in life. These foundational competencies are not merely tools for academic success but also empower individuals to navigate the complexities of modern life, engage in meaningful conversations, and make informed decisions. Thus, primary education fosters a lifelong love for learning, ensuring that children are equipped with the curiosity and ability to continue expanding their horizons.Nurturing Character and ValuesBeyond academic proficiency, primary education is vital in nurturing essential character traits and instilling values. During this formative period, children learn about empathy, respect, honesty, and responsibility—virtues that shape their identities and define their interactions with others. Classroom discussions, group activities, and extracurricular engagements all contribute to the cultivation of these values, helping students develop into well-rounded individuals capable of contributing positively to society.Breaking the Cycle of PovertyPrimary education plays a pivotal role in breaking the cycle of poverty and promoting economic growth. By providing children with the necessary skills and knowledge, they are better equipped to secure decent jobs, earn higher incomes, and lift themselves and their families out of poverty. Additionally, educated populations are more likely to innovate, invest in their communities, and contribute to a nation's overall prosperity. Therefore, investing in primary education is not just about educating today's children; it is an investment in the future economic stability and growth of entire nations.Fostering Global Understanding and CooperationIn an increasingly globalized world, primary education is also instrumental in fostering cross-cultural understanding and cooperation. By introducing students to diverse perspectives, languages, and cultures, they learn to appreciate and respect the uniqueness of others. This appreciation lays the foundation for peaceful coexistence, intercultural dialogue, and global collaboration—all of which are crucial for addressing the complex challenges facing humanity today, such as climate change, pandemics, and economic disparities.ConclusionIn conclusion, primary education stands at the forefront of personal, societal, and global development. It is a powerful force that equips individuals with the knowledge, skills, and values needed to navigate life's challenges and contribute meaningfully to their communities. By prioritizing primary education, we invest in the future, ensuring that the next generation has the tools and opportunities to build a brighter, more equitable, and interconnected world. As such, it is imperative that we continue to advocate for and support primary education globally, recognizing its irreplaceable role in shaping the future.。
primary study secondary study
primary study和secondary study都是学术研究中常用的术语，以下是它们的具体含义：primary study（初级研究）：这是从原始数据或者一手信息中进行的研究，方法包括但不
限于观察、实践、访谈、问卷调查等。
这些数据通常是研究者直接收集的，具有直接性、客观性和一手性。
在科学研究和社会研究中，初级研究的主要作用是提供客观的、可信的原始数据，从而为论证提供坚实的数据基础。
secondary study（次级研究）：这是利用已有的研究数据和信息进行分析和整合的研究方法。
它通过收集、评估和综合已有的研究成果、文献、统计数据和其他可得到的信息，以获得新的见解、总结或进行进一步的分析。
次级研究的数据来源主要是已有的文献或者其他二手数据。
以上是关于primary study和secondary study的信息，希望对您有所帮助。
小学用英语怎么说
小学用英语怎么说小学，是人们接受最初阶段正规教育的学校，是基础教育的重要组成部分。
那么你知道小学用英语怎么说吗?下面跟店铺一起学习小学的英语知识吧。
小学的英语说法primary schoolelementary schoolgrade school小学的相关短语小学英语 primary school English ; Primary English ; Primary English for China小学数学primary mathematics ; Elementary school mathematics ; Primary school mathematics南侨小学 Nan Chiau Primary ; Nan Chiau Primary School社会小学 Social School小学部Primary Section ; Grade School ; Junior School ; Primary school新民小学 Xinmin Primary ; Xinmin Primary School树群小学 Shuqun Primary ; Shuqun Primary School维新小学 West View Primary ; west view primary school康柏小学 Compassvale Primary ; Compassvale Primary School 小学的英语例句1. The boy first showed promise as an athlete in grade school.这个男孩在上小学的时候就初次显示出成为运动员的潜力。
2. Mrs Steele was head of Didcot's C of E primary school.斯蒂尔夫人曾是英国迪德科特圣公会小学的校长。
3. Truanting is a small but growing problem in primary schools.逃学是小学里一个虽小却日趋严重的问题。
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特词+情动+主语+动原+其它?
be动+主语+其它?
否回No, he isn’t.
谓语是实意动词：
Does he go to school every day? 肯回Yes, he does. Does +主语+动原+其它? 否回No, he doesn’t.
Do they go to school every day? Do+主语+动原+其它? 肯回Yes, they do.否回No, they don’t.
一般现在时态
定义 : 肯定句 谓语是be动词 谓语是实义动词 He is a teacher. 主语+be/动+其它 He goes to school every day. 主语+动变+其它 主语是三单 表示经常或习惯性发生的动作或存在的状态
They go to school every day.
MelodyClass
初级英语语法 一般现在时
动词： BE动词(is/am/are)
助动词（do/does/diห้องสมุดไป่ตู้/done/have/has)
情态动词（can/may/might/must...)
实意动词（play/eat/drink/make...)
人称代词 人 称 单 数
人称代词
主格 宾格
物主代词 形容性 物主代词 名词性代词
主语+ doesn’t + 动原+其它
单） 主语+don’t+ 动原+其它
They don’t go to school every day.
（主语非三
They can’t sing a song. 主语+情动+not+ 动原+其它
一般疑问句
谓语是be动词：
Is he a teacher?
肯回Yes, he is.
特殊疑问句
特殊疑问词：what when who whose where how which .... What is he? 特词+ be动+主语+其它? What does he do every day?
特词+ does +主语+动原+其它?
What do they do every day? 特词+ do+主语+动原+其它? What can they do?
划线部分就是复合谓语哦!
人称与动词配对
我是am ( i am =im) 你是are (you are ) is 跟着他她它 (he is ,she is ,it is) 复数全部都有are (we are,you are,they are) 一般现在时态，主语是三人称单数（简称三单），谓语动词后需要加 s或es，千万不可以忘记的哟. eg: she likes apples. It runs very fast. He watches tv everyday.
第一人称 我们
第二人称 你们
you
you
your
yours
yourselves
第三人称 他她它们
they
them
their
theirs
themselves
句子结构解析
I 主语 am 谓语 Chinese.
主语一般放句首 谓语一定要是动词哦 复合谓语：就是有两个动词或动词短语组成的谓语哦 比如：情态动词+动词原形 eg：she can dance well.
反身代词
第一人称 第二人称
我 你
I you
me you
my your
mine yours
myself yourself
第三人称
他
她 它
he
she it
him
her it
his
her its
his
hers its
himself
herself itsel
复
数
we us our ours ourselves
主语+动原+其它
主语不是三单
谓语是情态动词
They can sing a song.
主语+情动+ 动原+其它
主语不是三单
否定句 谓语是BE动词：He is not a teacher. 主语+ be动+not+其它
谓语是实意动词：He doesn’t go to school every day.(主语是三单）