SQL is a domain-specific language used in programming and designed for managing data held in a relational database management system, or for stream processing in a relational data stream management system. It is useful in handling structured data, i.e. data incorporating relations among entities and variables. SQL offers two main advantages over older read–write APIs such as ISAM or VSAM. Firstly, it introduced the concept of accessing many records with one single command. Secondly, it eliminates the need to specify how to reach e.g. with or without an index. Based upon relational algebra and tuple relational calculus, SQL consists of many types of statements, which may be informally classed as sublanguages, commonly: a data query language, a data definition language, a data control language, a data manipulation language; the scope of SQL includes data query, data manipulation, data definition, data access control. Although SQL is a declarative language, it includes procedural elements. SQL was one of the first commercial languages to utilize Edgar F. Codd’s relational model.
The model was described in his influential 1970 paper, "A Relational Model of Data for Large Shared Data Banks". Despite not adhering to the relational model as described by Codd, it became the most used database language. SQL became a standard of the American National Standards Institute in 1986, of the International Organization for Standardization in 1987. Since the standard has been revised to include a larger set of features. Despite the existence of such standards, most SQL code is not portable among different database systems without adjustments. SQL was developed at IBM by Donald D. Chamberlin and Raymond F. Boyce after learning about the relational model from Ted Codd in the early 1970s; this version called SEQUEL, was designed to manipulate and retrieve data stored in IBM's original quasi-relational database management system, System R, which a group at IBM San Jose Research Laboratory had developed during the 1970s. Chamberlin and Boyce's first attempt of a relational database language was Square, but it was difficult to use due to subscript notation.
After moving to the San Jose Research Laboratory in 1973, they began work on SEQUEL. The acronym SEQUEL was changed to SQL because "SEQUEL" was a trademark of the UK-based Hawker Siddeley Dynamics Engineering Limited company. After testing SQL at customer test sites to determine the usefulness and practicality of the system, IBM began developing commercial products based on their System R prototype including System/38, SQL/DS, DB2, which were commercially available in 1979, 1981, 1983, respectively. In the late 1970s, Relational Software, Inc. saw the potential of the concepts described by Codd and Boyce, developed their own SQL-based RDMS with aspirations of selling it to the U. S. Navy, Central Intelligence Agency, other U. S. government agencies. In June 1979, Relational Software, Inc. introduced the first commercially available implementation of SQL, Oracle V2 for VAX computers. By 1986, ANSI and ISO standard groups adopted the standard "Database Language SQL" language definition. New versions of the standard were published in 1989, 1992, 1996, 1999, 2003, 2006, 2008, 2011 and, most 2016.
SQL deviates in several ways from its theoretical foundation, the relational model and its tuple calculus. In that model, a table is a set of tuples, while in SQL, tables and query results are lists of rows: the same row may occur multiple times, the order of rows can be employed in queries. Critics argue that SQL should be replaced with a language that returns to the original foundation: for example, see The Third Manifesto. However, no known proof exists that such uniqueness cannot be added to SQL itself, or at least a variation of SQL. In other words, it's quite possible that SQL can be "fixed" or at least improved in this regard such that the industry may not have to switch to a different query language to obtain uniqueness. Debate on this remains open; the SQL language is subdivided into several language elements, including: Clauses, which are constituent components of statements and queries. Expressions, which can produce either scalar values, or tables consisting of columns and rows of data Predicates, which specify conditions that can be evaluated to SQL three-valued logic or Boolean truth values and are used to limit the effects of statements and queries, or to change program flow.
Queries, which retrieve the data based on specific criteria. This is an important element of SQL. Statements, which may have a persistent effect on schemata and data, or may control transactions, program flow, sessions, or diagnostics. SQL statements include the semicolon statement terminator. Though not required on every platform, it is defined as a standard part of the SQL grammar. Insignificant whitespace is ignored in SQL statements and queries, making it easier to format SQL code for readability. SQL is designed for a specific purpose: to query data contained in a relational database. SQL is a set-based, declarative programming language, not an imperative programming language like C or BASIC. However, extensions to Standard SQL add procedural programming language functionality, such as control-of-flow constructs; these include: In addition to the standard SQL/PSM extensions and proprietary SQL extensions, procedural and o
Li Wenhai is a veteran Singaporean actor. He has acted in various Singaporean television dramas. 1982Mother's Birthday Present 一束花 Evening Breeze 晚来风急1983Double Blessings 春风得意 as Li Ming Feng 李明峯 Endless Knots 情结 All that Glitters is Not Gold 捷径 A Breakfast Story 早餐的故事1984Spice of Life 四日谈 The Awakening 雾锁南洋 之《狮城拂晓》 as Zhao Zi Liang 赵子良 Blossoms in the Sun 阳光蜜糖 as Wu Tian Sheng 吴天生 The Awakening 2 雾锁南洋II–风雨同舟/赤道朝阳 Pursuit 怒海萍踪1985The Unyielding Butterflies 铁蝴蝶 as Huang Ji Ze 黄季泽 The Young Heroes 少年英雄 as Hui Tian Yu 惠天宇1986Men of Valour 盗日英雄传 as Zhang Bao 张保 The Samsui Women 红头巾 as A-Long 阿龙 Crossroads 红绿灯 之《绿影》 as Du Sen 杜森 The Bond 天涯同命鸟 as Chuan Qi Yi Fu 川崎一夫 The Sword and the Song 绝代双雄 as Li Yu 李煜1987Fury of the Dragon 冷月剑无言 as Xie Meng 谢猛 Strange Encounters 奇缘 之《辗转红尘》、《阴差阳错》 as Zha Kang Nian, Jin Gong Zi 查康年、金公子1988Airforce 空军 as Lu Wen Biao 陆文彪 The Last Applause 舞榭歌台 as Ma Duan Cheng 马端成 Mystery 迷离夜 之《梦》、《谜》 as Wei Xing 韦信 Strange Encounters 2 奇缘2 之《阴阳妻》 as Wen Bu Ting 温布庭1989A Long Way Home 燃烧岁月 as Zheng Wei Ting 郑伟庭 Return of the Prince 丝路迷城 as Yi Bei Da Shi 一杯大师1990Navy 壮志豪情 as Zhang Zhao Hua 张兆华 The Winning Team 飞跃巅峰 as Fang Zhi Hui 方志晖1991Behind Bars 铁狱雷霆 as Lawyer 律师 The Other Woman 醋劲100 as Ding Shi Hong 丁世鸿1998Riding the Storm 陌生人 as Dong Shou Lian 董守廉1999From the Medical Files 2 医生档案II as Li Yu Feng 李裕丰 Stepping Out 出路 as Chen Jia Geng 陈嘉庚 Hero of the Times 新方世玉2000Hainan Kopi Tales 琼园咖啡香 as Long Fu Yuan 龙甫远2001The Stratagem 世纪攻略 as Li Wan Shan 李万山 Heroes in Black 我来也 as King of Kang 康王 Love Me, Love Me Not 真爱无敌 as Shen Fei 沈非 The Challenge 谁与争锋 as Bai Ji Xiong 白继雄 The Hotel 大酒店 as Mr. Li 李先生2002Health Matters 一切由慎开始 The Vagrant 豹子胆 as Jia Bo 家泊 Fantasy 星梦情真 as Zheng Yi 郑义 Blueprint - The Bra Shop as Trishaw Lee 2003Home In Toa Payoh 家在大巴窑 as Zheng Da Ba 郑大跋2004The Crime Hunters 心网追凶 as Lin Xing Wang 林星旺 To Mum with Love 非一般妈妈 as Bai Shi Cong 白士聪 Beautiful Trio 大女人小女人 as Zeng Ying Xiong 曾英雄2005Destiny 梦在手里 as Si Qi's Father 思琪父亲
Yoshitomo Tokugawa was the 4th-generation head of the Tokugawa Yoshinobu-ke, the branch of the Tokugawa line started by the last Shōgun Tokugawa Yoshinobu. Born in Sena, in Shizuoka Prefecture, he went to school in Tokyo engaging in a career in photography and graphic design with Honda. A freelance author, he spent his time writing about the history of his family after the Meiji Restoration, he sold coffee under the brand name Tokugawa Shōgun Kōhī. Through his mother's side of the family, Yoshitomo is a descendant of Matsudaira Katamori. Yoshitomo died on September 25, 2017 in a hospital in Mito, Ibaraki Prefecture at the age of 67. Tokugawa Yoshinobu-ke ni Youkoso. Tokyo: Bungei-shunju, 2003. Tokugawa Yoshinobu-ke no Shokutaku. Tokyo: Bungei-shunju, 2005. Tokugawa, Yoshitomo. Tokugawa Yoshinobu-ke ni yōkoso: waga ie ni tsutawaru aisubeki "saigo no shōgun" no yokogao. Tokyo: Bunshun-bunko, 2005