Values Already Exists in the table

Question

I have one table like this ...
Pk EmployeeiD Date Time
1 Emp1001 5/8/2012 00:03:02
2 Emp1001   5/9/201200:03:02
3 Emp1001   5/10/201200:00:49

the above values are inserted successfully.....in their respective dates....

If i insert the above values again in the same table means

(ie..)Employeeid Date Time
  Emp1001 5/9/2012 00:03:02

it will show some message like (Date Already Exists)....

I didnt use Constraints in my table... I didnt know about constraints...am a Beginner

Anil Kumar · Answer

@Kundal I didn't get you please clear

Kunal Vaishya · Answer

Dear please is there primary key value duplicate or not my be it possible

Anil Kumar · Answer

addition to Jitendra make emplyeeID field as primary key by right-clicking on the column name after opening your table in design mode.

Jiteendra Sampathirao · Answer

Better to use constraints.... Below link is good one http://www.dotnetfunda.com/forums/thread6442-check-if-an-username-already-exists-in-the-database.aspx http://www.daniweb.com/software-development/csharp/threads/177604/check-whether-username-alraedy-exists-in-database Modify these code to your requirement.. Hope it help you..