C＃：使用linq将数据插入数据库

Question

i want to insert the data into my database, using linq. i follow the instruction , then i do some coding here, based on the followed instruction

 private void addNasabah()
    {
        char gender = cekRadio();

        customer customer = new customer()
        {
            nomor_customer = int.Parse(innomor.Text),
            nama = innama.Text.ToString(),
            jenis_kelamin = gender,
            alamat = inalamat.Text.ToString(),
            nomor_telepon = innomor.Text.ToString(),
            saldo = 0
        };

        dc.customers.InsertOnSubmit(customer);
        try
        {
            dc.SubmitChanges();
            cmd.cetakSukses("Berhasil Menyimpan Nasabah", "Tambah Nasabah");
            innomor.Text = genNextId().ToString();
        }
        catch (Exception e)
        {
            cmd.cetakGagal(e.ToString(), "Tambah Nasabah");                                
        }

    }

here is cekRadio() method

 private char cekRadio()
    {
        if (radioButton1.Checked)
        {
            return 'p';
        }
        else
        {
            return 'w';
        }
    }

but i encountered some error, here's the error

the picture said "input string was not in a correct format" .

what is the expected string correct format ?

here is my genNextId() method

  private int genNextId()
    {
        int id = (from a in dc.customers
                  select a.nomor_customer).Max();

        return id+1;
    }

i try running the application, the messagebox showed "Berhasil Menyimpan Nasabah", "Tambah Nasabah" but then i checked in my database, the entered data wasn't there.

here is my customer table on the database

Answer 1

Put a break point next to this line Customer customer = new Customer() and you can now check what the value of each variable is, the int.Parse() could be an issue if the string is not able to be parsed into an integer .

Also, make sure the properties of Customer are the expected types , check jenis_kelamin for example.

Another (unrelated to bug) point, if you're using Object Initializer ie new Object {} , then you can drop the parenthesis (), so you would have...

Customer customer = new Customer { ..properties.. };

EDIT : In light of some of the comments you have posted, I need to point out the way you are retrieving the Next ID is a bad approach. I specified in one of the comments above that you should use an Identity field in SQL, this way you set the seed and increment , and SQL will generate the next ID on your behalf.