Check dublicate from inSQL while inserting Data from UI C#

Question

Check dublicate from inSQL-DB while inserting Data from UI in C#.

 

Consider two textbox as -EMP-CODE and NAME...

 

i want insert somethink to SQL_DB. but while inserting it should check dublicate data in  DB.

If dublicate exist  it wont allow to insert in DB.

 

Giving a msg..dublicate data not allowed....???

 

pls help