Search results
Results from the WOW.Com Content Network
For example, think of A as Authors, and B as Books. An Author can write several Books, and a Book can be written by several Authors. In a relational database management system, such relationships are usually implemented by means of an associative table (also known as join table, junction table or cross-reference table), say, AB with two one-to-many relationships A → AB and B → AB.
Storm, open source (LGPL 2.1) developed at Canonical Ltd. Tryton, open source; web2py, the facilities of an ORM are handled by the DAL in web2py, open source; Odoo – Formerly known as OpenERP, It is an Open Source ERP in which ORM is included.
Object–relational mapping (ORM, O/RM, and O/R mapping tool) in computer science is a programming technique for converting data between a relational database and the memory (usually the heap) of an object-oriented programming language.
The entity–relationship model proposes a technique that produces entity–relationship diagrams (ERDs), which can be employed to capture information about data model entity types, relationships and cardinality. A Crow's foot shows a one-to-many relationship. Alternatively a single line represents a one-to-one relationship. [4]
In computing and data management, data mapping is the process of creating data element mappings between two distinct data models. Data mapping is used as a first step for a wide variety of data integration tasks, including: [1] Data transformation or data mediation between a data source and a destination
One notation as described in Entity Relationship modeling is Chen notation or formally Chen ERD notation created originally by Peter Chen in 1976 where a one-to-many relationship is notated as 1:N where N represents the cardinality and can be 0 or higher. A many-to-one relationship is sometimes notated as N:1. [2]
M:N maps some M number of application threads onto some N number of kernel entities, [9] or "virtual processors." This is a compromise between kernel-level ("1:1") and user-level (" N :1") threading. In general, " M : N " threading systems are more complex to implement than either kernel or user threads, because changes to both kernel and user ...
The "N" in an N 2 diagram is the number of entities for which relationships are shown. This N × N matrix requires the user to generate complete definitions of all interfaces in a rigid bidirectional, fixed framework. The user places the functional or physical entities on the diagonal axis and the interface inputs and outputs in the remainder ...