翻訳と辞書 Words near each other ・ presto ・ pretty amazing new stuff ・ pretty good privacy ・ pretty pictures ・ prettyprint ・ pretzel key ・ preventive maintenance ・ pri ・ primary cache ・ primary domain controller ・ primary key ・ primary management domain ・ primary rate interface ・ primary storage ・ prime computer ・ prime number theorem ・ prime time ・ primenet, inc. ・ primitive ・ princeton university Dictionary Lists mini英和辞書 mini和英辞書 Webster 1913 Latin-English FOLDOC Wikipedia English ウィキペディア

翻訳と辞書　辞書検索 [ 開発暫定版 ] スポンサード リンク primary key ： FOLDOC primary key A unique identifier, often an integer, that labels a certain row in a table of a relational database. When this value occurs in other tables as a reference to a particular row in the first table it is called a "foreign key". Some RDBMSes can generate a new unique identifier each time a new row is inserted, others merely allow a column to be constrained to contain unique values. A table may have multiple {candidate keys}, from which the primary key is chosen. The primary key should be an arbitrary value, such as an {autoincrementing} integer. This avoids dependence on uniqueness, permanence and format of existing columns with real-world meaning (e.g. a person's name) or other external identifier (e.g. social security number). There should be enough possible primary key values to cater for the current and expected number of rows, bearing in mind that a wider column will generally be slower to process. (2006-05-29) スポンサード リンク 翻訳と辞書 : 翻訳のためのインターネットリソース Copyright(C) kotoba.ne.jp 1997-2016. All Rights Reserved.