DATABASE DESIGN in SQL Server:-
Steps followed in database development:
- Db designed by “DB Designer(or) DB Architect”
- The DB designer designed the db by using two techniques,
(i) ER model: Top-down Approach
(ii) Normalization: Bottom up Approach
- DB developed by “DB Developer”
- The developer the will develop the database by using “RDBMS TOOL” i:e sql server (or) oracle.
ER MODEL in SQL Server :–
- ER stands for “entity relationship” model
- It is a “Graphical representation of data”.
- The diff. element of ER model
- Entity sets
ENTITY in SQL Server with Example:–
- It is an object.
Ex: Employee,customer,bank A/c,course etc.
ENTITY SETS in ER Diagram with Example:–
- Collection of entities that share common properties is called “Entity Sets”.
Symbol: rectangle represents the entity set.
Examples of ATTRIBUTES in Database:–
- Attributes one the properties of entity.
Empid ename job sal
These are all properties of employee.
- Attributes are indicated by symbol is “Oval or Ellipse”.
RELATIONSHIPS in SQL Server :–
- A relationship is a association b/w entities of entity sets.
- The relationship is indicated by symbol is “dimension”
Types of Relationships in SQl Server :–
- 1 to 1
- 1 to many
- Many to Many
- ER model can be used to at “Design part”
Difference Between ER model and Relational Model
ER Model Relational Model
Entity sets Here,entity sets are converted to “Tables”
Relationships “Foreign keys”