LeynaLeyna Database Chapter 7

Database basic knowlodge

database application: a particular database and the associated programs that implements the databse queries and updates.

GUI: graphical user interfaces

Database design process:

• requirenments collection and analysis
• create a conceptual schema->conceptual design(this chapter focus on this point)
• logical design
• phisical design

##ER Model##
Entity: a thing in the real world with an independent existence
Attributes: the particular properties that describe the entity.

• simple – composite
• single-value – multivalued
• stored – dereived(Age is a derived attribute derivable from birthday)
• null values(college_degree for a person don’t have;unknow)
• complex attribute: combination of composite and multivalued

weak entity type: an entity type with no key