Part i:relational Databases and SQL
Chapter2, ensuring Your Database Structureis sound.
Database Design Guidelines
What is a relational database
RDBMS (A relational database management systems) relational database
Tables
Tables is the mainstructures in the database. Each table always represents a
Single, Specificsubject.
Fields
A field is thesmallest structure in the database, and it represents a characteristic
of the subject ofthe table to which it belongs.
Records
A record Representsa unique instance of the subject of a table.
Keys
Keysare Special fields that play very specific roles within a table. eg.
The primary key role is to ensure the uniqueness of the data record, that is, the primary key constraints to ensure that all data records in a database table are different individuals, for example: The ID number can guarantee a person in the mainland is a separate individual (not counted), That is, an identity card number can not identify two persons or two identification number identification of a person. So the primary key is analyzed from the existing data, not the designer arbitrarily added.
Relationships
SQL query Beginner's Guide reading notes (i) relational database and SQL introduction