D., Some problems concerning keys for relation scheme and relations in the relational datamodel, Information Processing Letters, North Holland, 46 (4) (1993) 179-183.Demetrovics J., Thi V.D. Some Problems concerning Keys for Relation Schemes and Relations in the Relational Datamodel. ...
Relationsmodel (RM)repræsenterer databasen som en samling af relationer. En relation er intet andet end en værditabel. Hver række i tabellen repræsenterer en samling af relaterede dataværdier. Disse rækker i tabellen angiver en entitet eller relation i den virkelige ...
21, 1932. [Class 39 (i)] In a Br... SCHLESINGER KURT 被引量: 97发表: 1935年 E-R模型中联系状态研究及应用 The translating of Entity-Relationship model into Relational Data model is an important process of a database design. There are some defects in the traditi... 梁玉强 - 《计算机...
1.Determination ofrelational expressionfor running adjustment of heating system;供暖运行调节关系式的试验确定 2.After analyzing those curves,we derived therelational expressionof the MDEA solutions s kinetic viscosity on temperature and volume concentration.对不同曲线进行分析回归,得出甲基二乙醇胺的动力粘度与...
A graphical data modeling tool, allowing one to build Entity-Relation data models for use with Relational Databases (RDBMS). 这是个图形化的数据建模工具,可创建使用关系数据库的实体-关系数据模型。 dict.bioon.com 5. Based on Program Architecture Description Language-NEWCOM, introduces the procedure of...
DBMS - Relation Data Model - Relational data model is the primary data model, which is used widely around the world for data storage and processing. This model is simple and it has all the properties and capabilities required to process data with storage
An alternative definition of the concept is given of functional dependence among the attributes of the relational schema in the Relational Model, this definition is obtained in terms of the set theory. For that which a theorem is demonstrated that establishes equivalence and on the basis theorem an...
Note that all model propertiesare optional, includingrelational properties. findFirst Returns the first entity that satisfies the given query. constuser=db.user.findFirst({where:{id:{equals:'abc-123',},},}) findMany Returns all the entities that satisfy the given query. ...
The fourth part of the relational data theory A single choice 1. the relationship between the standardization of the delete operation refers to abnormal, abnormal refers to the insert operation.A. is not the deleted data is deleted B. not the inserted data is inserted C. should be deleted ...
A relational database consists of a collection of tables, each of which is assigned a unique name. An example is the table below: When we consider this table, a row in the table can be thought of as representing the relationship