1] Strong Entity Set:

• A strong entity set reduces to schema with same attributes.

• If E is strong entity set with descriptive attributes $a_1. . . a_n$ This entity set will be represented as E with n distinct attributes.

2] Weak entity set:

• Schema is a combination of primary key from identifying strong entity set and attributes of weak entity set.

3] Relationships:

a] One to one.

• Extra attribute is added to either of entity set schema corresponding to entity set participating in relationships.

b] Many to one/one to many.

• Extra attribute is added to many side entity set with primary key of one side entity set as a foreign key constraint.

c] Many to may.

• A separate schema is created with primary keys of participating schema.

4] Multi valued attribute:

• A separate schema is created with multi valued attribute and primary key of entity of entity whose multi valued attribute.

5] Composite attribute:

• These attributes are flattered to its constituent attributes.

6] Derived attribute:

• These attributes are ignored as their values can be derived from other attributes.