ORM uses information of this display for process control of data transformation between a basis and forms of objects, and also for creation of SQL queries for an insertion, up-dating and deleting data in response to changes which the application makes to these objects.ĭistributed database – a set of the separated data which are logically connected among themselves (and their descriptions) which are physically distributed on some computer network. Display shows as an object and its properties are connected to one or several tables and their fields in the database. ORM as if creates the "virtual" database scheme in memory and allows to manipulate data already at the object level. Principle of operation of ORM-Key feature of ORM is display which is used for an object binding to its data in a DB. ORM provides complete division of tasks in well programmed applications in case of which both the database, and the application can work dataful everyone in the root form. The majority of ORM tools considerably rely on meta data of the database and objects so objects need to know nothing about a database structure, and the database - nothing about how data are organized in the application. ORM is used for simplification of process of saving objects in a relational database and their extraction, in case of this ORM itself cares for data transformation between two incompatible statuses. ORM or Object-relational mappingis a technology of programming which allows to transform incompatible types of models to OOP, in particular, between the data store and subjects to programming. Besides, specifics of specific DBMS in case of physical design include a choice of the decisions connected to a physical medium of data storage (a choice of methods of management of disk memory, division of a DB according to files and devices, data access methods), creation of indexes etc. Specifics of specific DBMS can include restrictions for naming of database objects, restrictions for the supported data types, etc. Physical design - creation of the database scheme for specific DBMS. This stage can be substantially automated.Īt a stage of logic design specifics of a specific data model are considered, but specifics of specific DBMS can not be considered. For a relational data model data logical model - a set of diagrams of the relations, it is normal with specifying of primary keys, and also the "communications" between the relations representing foreign keys.Ĭonversion of conceptual model to a logical model is, as a rule, carried out by the formal rules. Logic design - creation of the database scheme on the basis of a specific data model, for example, a relational data model.
description of integrity constraints, that is requirements to admissible values of data and to communications in between.description of information objects or concepts of data domain and communications in between.Most often the conceptual model of the database includes: Graphic notations, similar to ER charts are usually used. The specific type and the maintenance of conceptual model of the database is defined by the formal device selected for this purpose. The terms "semantic model", "conceptual model" are synonyms. Such model is created without orientation to any specific DBMS and a data model. Abbreviation of redundance and duplicating of data.Ĭonceptual design - creation of a semantic domain model, that is information model of the highest level of abstraction.
(50) NOT NULL,ĬONSTRAINT PRIMARY KEY CLUSTERED IF NOT EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'.') AND type in (N'U')) What I am worried about is my transaction table interacting with my order table. I have developed an .aspx application for online payment processing and I am not sure if I setup the Relational Database correctly.
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