System Analyst Notes-database

Database:
Derived property: A property whose value can be derived from the value of a related property and property set.
Multivalued attribute: A property that is represented by multiple values at the same time.
Data mining: Use a range of technologies to extract information and knowledge that people are interested in from large databases or data warehouses. 1, decision tree. 2, neural network. 3, Genetic algorithm. 4, association rule Mining algorithm.
Data mining analysis methods are divided into 4 kinds: correlation analysis, Sequence pattern analysis, classification analysis, cluster analysis.
Naming conflicts: Properties of the same meaning, different names on different e-r charts, or attributes with the same name represent different meanings in different e-r diagrams.
Attribute conflict: Refers to the same attribute in different e-r diagrams, the type of the property, the range of values, and the data units may be inconsistent.
Structure conflict: The same entity is abstracted as an entity in one of the E-r diagrams, while in the other e-r the image is abstracted as an attribute.
Database design:
Requirements Analysis: Collect and analyze the information needs and processing requirements of the users, get the required information of the design system, and establish the system documentation.
Conceptual structure Design: all the data and processing requirements provided by the requirement are abstracted and synthesized, and the data of user environment and their interrelated conceptual model are constructed according to certain crime, namely user's data model or enterprise data model.
Logical design: translates to a conceptual pattern represented by a logical model accepted by a particular DBMS.
Physical design.

Database integrity: Data correctness, validity, compatibility (consistency).
The attributes contained in any one of the candidate keywords become the main property, ... A non-primary property.

View for Outer mode, table corresponding mode, store file for internal mode.

System Analyst Notes-database