Below is a description of the ER diagram for the Employee and Department tables before performing the DDL operations. 

Entity-Relationship (ER) Diagram

Entities

1. Employee

   • Attributes:

     • Emp_No (Primary Key)

     • Emp_Name

     • Designation

     • Designation_NO

     • SAL

     • COMMISSION

2. Department

   • Attributes:

     • Dept_ID (Primary Key)

     • Dept_Name

Relationships

1. WorksIn

   • Attributes:

     • Designation_NO (Foreign Key referencing Dept_ID in Department)

EER Diagram

Explanation

1. Employee Entity:

   • Contains attributes such as Emp_No, Emp_Name, Designation, Designation_NO, SAL, and COMMISSION.

   • Emp_No is the primary key.

   • Designation_NO is a foreign key that references Dept_ID in the Department table.

2. Department Entity:

   • Contains attributes such as Dept_ID and Dept_Name.

   • Dept_ID is the primary key.

3. WorksIn Relationship:

   • Represents the relationship between Employee and Department.

   • The foreign key Designation_NO in the Employee table references Dept_ID in the Department table.