I have a doubt on creation of my sql database..can anyone please explain me..

I have two dropdownlist named department and semester... In department i have 8 branches and in Semester i have 8 semesters..If i select department and semester details regarding that branch and semester should appear like assigned date,deadline date,subject,work description,assigned to....

How should i create my database whether it should be seperate tables for each branch and each semester..

If you're using SQL server for your database then you're using a relational database environment which allows you to utilize linked tables with related information.

What I might suggest is you check these tutorials on creating relational databases as they may help you decide your DB setup.

Hope that helps.