database schema for messaging system

Tags: data model organization logical Encapsulation attribute set restriction conceptual mode contactThe 15th Chapter Object Relational database systemObject Relational database System (OPRDBS) is a product of the combination of object-oriented data model (OO model) and relational data model.An OO model is a model that describes the logical organization of real-w

of local data currently in use), patterns (also called logical Schema, which is the description of the logical structure and characteristics of all data in the database), internal mode (also known as storage mode, is the representation of data within the database system) Data independence: Data independence includes t

DB2 virtual system mode or as part of a DB2 database workload pattern. As described in previous articles in this series, the DB2 virtual system model supports more flexible control and configuration of the middleware environment. Currently, multiple images can be deployed as DB2 virtual system mode: DB2 Enterprise D

, that is, from a security perspective to consider the excess of a quantity, which is to ensure that the instrument, equipment or a work under normal conditions can also operate normally. Data independence means that the application and data structures are independent from each other and are not affected. Data independence includes data logical independence and data physical independence. Extensibility is the degree to which you can upgrade, and the more scalable you are, the more space you will

A distributed Database systemDistributed Database system: A physically dispersed and logically centralized database system.Physical dispersion: Refers to the sites scattered in different places. Big can be different countries. The few are different locations of the same building.Logically focused: means that the sites

A distributed Database systemDistributed Database system: A physically dispersed and logically centralized database system.Physical dispersion: Refers to the site scattered in different places, large can be different countries, and the same buildings in different locations.Logically centralized: refers to each site is

) semistructured Data ModelIn a semi-structured data model such as XML, the data is allowed to have different fields, which is not the same as the previous model.third, the database languageSQL contains DDL (data-definition language) and DML (Data-manpulate language).A) DMLDML is used to manipulate data such as additions and deletions, divided into process DML and non-procedural DML, the former in use to specify the need to manipulate the data and the

Database integrity (db Integrity) refers to the correctness and compatibility of data in a database. Database integrity is guaranteed by a variety of integrity constraints, so it can be said that database integrity design is the design of database integrity constraints.

Structure database structure of database systemDevelopment StaffThree-level mode for system architecture within the database systemSchema (Schema)Description of the logical structure and characteristics of the databaseType, not a specific valueRelatively stableExample (Insta

51cto College, in the soft exam preparation season specially organized the "2014 Soft test-database Systems Engineering-Knowledge point explain" summary ", to help you pass the school smoothly! More software proficiency test Counseling and questions, please follow 51cto College-soft Test classification bar View Summary:2014 Soft Test-database Systems Engineering-Knowledge Point explained "summary

The three-level structure of the database system refers to that the database system consists of three levels: mode, external mode, and internal mode.(1) The mode is also called the logical mode or conceptual mode. It is the logical structure and feature description of all data in the

Label:First, the SQL database architecture key points are as follows: 1. A SQL schema (scheme) is a collection of tables and constraints;----->SQL Mode (scheme) aka Database 2. A table consists of a rowset, a row is a sequence of columns, each column corresponds to a data item; 3. There are three types of tables: basic tables, views, export tables. A base table i

SQL Server system databases are important, and they should not be modified most of the time. The only exception is the model database and the tempdb database. The model database allows deployment changes to any newly created database, such as a stored procedure, and the temp

Tags: best performing asynchronous write core evaluation Metrics capabilities Overview Migration synchronizationOverviewThe necessity of the Sub-database tableFirst, let's look at why we want to do a sub-database table. In our business (Web application), the relational database itself is relatively easy to become a system