user defined error message

Question

How to show user defined error messages in Windows application using c#? (e.g) When duplicate value is entered in database I have to show Already value exists in that name.....

Piyush chhabra · Answer

To show user defined error message You should throw the exception with Your message in parameter. For example If you call an Method/Function which is only declared and you have not written any code in the body then NotImplementedException Exception will be used. So you can throw the exception in the body of Method/function like this --> public int MyFunction() { throw new NotImplementedException( This is exception throwing Example ); } Now for Checking in Database You can simply run the query. For example you dont want the same Email address then use this query. string Email = select count(*) from studentdata where Email=' + TextBox1.Text + '; SqlCommand com = new SqlCommand(Email con); \ here con is Sqlconnection class object int temp=Convert.ToInt32(com.ExecuteScalar().ToString()); Now if there is any email address present in table then the value of temp will be 1  Otherwise it will be 0. Now you can simply use If-Else if(temp==1) { \code to add email address } else { \your Error Message }

Gowtham Rajamanickam · Answer

public int MyFunction() { throw new NotImplementedException( This is exception throwing Example ); }