INFO MAG LESSON 3: Relational Data Model

• Relational Data Model- Represent data in the form of tables
• Relation- A named, two-dimensional table that consists of a column and arbitrary number of rows
• Attribute- named column
• Record- each row of relation that contains data
• Required Attributes- the filed need to have an input. Is not NULL
• Optional Attribute- you can leave the field blank. can be NULL
• Simple- can only have ONE field
• Composite- can be broken into pieces and have many field for that column
• Single-valued- contains single value
• Multivalued- can have many values inputted to the field
• Stored- ang ininput mo ay same padin
• Derived- the value you inputed can be compute by other columns
• Identifier- Must not change in value. Must not be null. Must be unique
• Primary Key- an attribute or a combination of attributes that

  uniquely identifies each row in a relation
• Foreign Key- attribute used to establish the relationship between

  two tables. This always point to the primary key.
• Composite key- a key that consists of more than one attribute
• Domain Constraints- Domain is a set of values that can be

  assigned to an attribute ; a domain definition consists of domain

  name, meaning, data type, size and allowable values for the

  domain values
• Entity Integrity- ensures that every relation has a valid

  primary key
• Referential Integrity- rule that maintains consistency among

  the rows of two relations.