Evaluation to candidate keys by functional dependencies in the database 数据库中利用函数依赖求解候选码的方法
Unique , primary key , referential , check , and functional dependency constraints are supported 惟一约束、主键约束、参照约束、检查约束和函数依赖约束在这里都受支持。
A normalized database prevents functional dependencies in the data so that updating the database is easy and efficient 规范化的数据库可防止数据存在功能相关性,以便轻松、高效地更新数据库。
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:讨论了含空值关系数据库中函数与多值依赖,并给出了有关的定义、规则与定理
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 研究工作的重点是使用概念格结构模型对关联规则、分类规则和函数依赖的发现问题进行求解。
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 通过把xml键约束映射为关系数据库中的函数依赖,在更新xml文档时,不但保持了xml文档本身的键约束,还使关系数据库和xml文档保持了一致。
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 主题包括:关联式资料库、 sql (结构查询语言) ;资料类型、关联、关联式代数、完整性、景观表;功能依附理论、正规化、语义塑模、实体关联塑模、概念性资料库设计;同时操作控制、安全;资料库与网页连结、 xml (可扩展标示语言) 。
百科解释
In relational database theory, a functional dependency is a constraint between two sets of attributes in a relation from a database.