Data Relational Model

1. Natural Join

1.1. Links tables by selecting rows with common values in common attribute(s)

2. Relational Set Operator

2.1. Equijoin

2.1.1. Links tables on the basis of an equality condition that compares specified columns

2.2. Theta Join

2.2.1. Any other comparison operator is used

2.3. Outer Join

2.3.1. Matched pairs are retained, and any unmatched values in other table are left null

3. Characteristic of Relational Table

4. Integrity Rule

4.1. Entity Integrity

4.2. Referential integrity

5. Key

5.1. Super Key

5.2. Candidate Key

5.3. Primary Key

5.4. Foreign Key

6. Relationship

6.1. One-to-Many

6.2. One-To-One

6.3. Many-To-Many