Evaluation to candidate keys by functional dependencies in the database 數(shù)據(jù)庫中利用函數(shù)依賴求解候選碼的方法
Unique , primary key , referential , check , and functional dependency constraints are supported 惟一約束、主鍵約束、參照約束、檢查約束和函數(shù)依賴約束在這里都受支持。
A normalized database prevents functional dependencies in the data so that updating the database is easy and efficient 規(guī)范化的數(shù)據(jù)庫可防止數(shù)據(jù)存在功能相關(guān)性,以便輕松、高效地更新數(shù)據(jù)庫。
Abstract : the functional dependency and multiple valued dependency in the relational database with null values are discussed . and the related defintions , rules and laws are given 文摘:討論了含空值關(guān)系數(shù)據(jù)庫中函數(shù)與多值依賴,并給出了有關(guān)的定義、規(guī)則與定理
The main research work is to make use of concept lattice structure to solve the problem of mining association rules , classification rules , and functional dependencies from data 研究工作的重點(diǎn)是使用概念格結(jié)構(gòu)模型對關(guān)聯(lián)規(guī)則、分類規(guī)則和函數(shù)依賴的發(fā)現(xiàn)問題進(jìn)行求解。
By propagating xml keys to relations as functional dependencies , we update xml data and it ' s storage over relational databases at the same time , we preserve the coincidence between them 通過把xml鍵約束映射為關(guān)系數(shù)據(jù)庫中的函數(shù)依賴,在更新xml文檔時,不但保持了xml文檔本身的鍵約束,還使關(guān)系數(shù)據(jù)庫和xml文檔保持了一致。
Topics include : relational databases , sql ( structured query language ) ; types , relations , relational algebra , integrity , view ; functional dependency theory , normalization , semantic modeling , entity - relationship modeling , conceptual database design ; concurrency control , security ; database and web connectivity , xml 主題包括:關(guān)聯(lián)式資料庫、 sql (結(jié)構(gòu)查詢語言) ;資料類型、關(guān)聯(lián)、關(guān)聯(lián)式代數(shù)、完整性、景觀表;功能依附理論、正規(guī)化、語義塑模、實(shí)體關(guān)聯(lián)塑模、概念性資料庫設(shè)計;同時操作控制、安全;資料庫與網(wǎng)頁連結(jié)、 xml (可擴(kuò)展標(biāo)示語言) 。
百科解釋
In relational database theory, a functional dependency is a constraint between two sets of attributes in a relation from a database.