Database Design Process
Requirements Analysis: The data flow diagram, a data dictionary - "generation requirements specifications .
Design concept: the completion of the ER model modeling work (ER model independent of the specific DBMS, you can get mysql database, you can also get oracle database, etc.).
Logic Design Structure: relational schema (logical structure design of the product, by conversion of the model come ER)
Physical design stage: taking into account the DBMS and hardware systems are taken into account.
ER model
Contact type entities
Relational schema
Mode is a way to describe the database, the database in which for explaining the table, the table those columns, these structures, to design a database structure meet the functional requirements.
In the design, often we need to consider how to abstract the actual needs of the conversion, to avoid redundancy and errors of the model relationship model, which is the logical database design issues.
Particularly it relates to a first paradigm, the second paradigm, the third paradigm.
ER model turn relational schema
One on one contact can be placed on either side .
Many , contact can only be placed more than one party .
Many to many, contact must be transferred into a single relational schema.
