Problems Inserting Char() Type into MySql Table Structure

Question

please help to examining the following code snippet :

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the compiler highlight the exception caused syntax If (mycommand.ExecuteNonQuery() > 0) Then bSaved = True
with the message "MySqlException was Unhandled; Column "id_cust" cannot be null"

please help to be patiently delve deeper the following code:
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VB CLASS : MyProspek.vb*

Imports MySql.Data
Imports MySql.Data.MySqlClient

Public Class MyProspek

Inherits System.Collections.Hashtable

Private fKey As String() = {"id_cust", "nama", "kota", "tgl_lahir", "telpon", "hobbies", "titel",  _ "pekerjaan","jkelamin", "kawin", "opini", "maksud"}


Public Sub New()

End Sub


Public Sub New(ByVal prospList As Hashtable)
For j As Integer = 0 To prospList.Count - 1
Add(fKey(j), prospList.Item(fKey(j)))
Next
End Sub

Public Function Append(Optional ByVal ListProsp As Hashtable = Nothing) As Integer
If (ListProsp Is Nothing) Then
Return 0
Else
For j As Integer = 0 To ListProsp.Count - 1
Add(fKey(j), ListProsp.Item(fKey(j)))
Next
End If
Return Count
End Function

Public Function Save() As Boolean
Dim bSaved As Boolean = False
Dim myconn As MySqlConnection = Nothing
Dim mycommand As MySqlCommand = Nothing
Dim strSQL As String = Nothing
Dim n As Integer = 0
Dim connsql As String = "server=localhost; user id=root; password=; Database=Test1; pooling=false"


myconn = New MySqlConnection(connsql)
myconn.Open()

For n = 0 To (Count / Count) - 1
strSQL = "insert into tprospek(id_cust,nama,kota,tgl_lahir,telpon,hobbies,titel,pekerjaan,jkelamin,kawin,opini,maksud)" + _
" values(@p0,@p1,@p2,@p3,@p4,@p5,@p6,@p7,@p8,@p9,@p10,@p11)"

mycommand = New MySqlCommand(strSQL, myconn)

mycommand.Parameters.AddWithValue("@p0", Item(n))
mycommand.Parameters.AddWithValue("@p1", Item(n + 1))
mycommand.Parameters.AddWithValue("@p2", Item(n + 2))
mycommand.Parameters.AddWithValue("@p3", Item(n + 3))
mycommand.Parameters.AddWithValue("@p4", Item(n + 4))
mycommand.Parameters.AddWithValue("@p5", Item(n + 5))
mycommand.Parameters.AddWithValue("@p6", Item(n + 6))
mycommand.Parameters.AddWithValue("@p7", Item(n + 7))
mycommand.Parameters.AddWithValue("@p8", Item(n + 8))
mycommand.Parameters.AddWithValue("@p9", Item(n + 9))
mycommand.Parameters.AddWithValue("@p10", Item(n + 10))
mycommand.Parameters.AddWithValue("@p11", Item(n + 11))

MySqlException was Unhandled: 'Column "id_cust" cannot be null
If (mycommand.ExecuteNonQuery() > 0) Then bSaved = True
Next
Return bSaved
End Function

End Class


The Consumer Class in Form1.vb*

Public Class Form1

Private Sub BttnSimpan_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles BttnSimpan.Click

Dim mylist As New Hashtable()

Dim mypelanggan As MyProspek = Nothing

Dim str As String = IDText1.Text.Trim

Dim lchr As Char() = str.ToCharArray()

mylist.Add("id_cust", lchr)

mylist.Add("nama", txtNama.Text.Trim)

mylist.Add("kota", txtTempat.Text.Trim)

mylist.Add("tgl_lahir", DTPicker1.Value)

mylist.Add("telpon", txtTelpon.Text.Trim)

mylist.Add("hobbies", txtHobbies.Text.Trim)

mylist.Add("title", cboGelar.Text.Trim)

mylist.Add("pekerjaan", txtPekerjaan.Text.Trim)

mylist.Add("jkelamin", If((rdoPria.Checked), "1", "0"))

mylist.Add("kawin", If((rdoYa.Checked), "1", "0"))

mylist.Add("opini", txtOpini.Text.Trim)

mylist.Add("maksud", txtMaksud.Text.Trim)

mypelanggan = New MyProspek()

mypelanggan.Append(mylist)

If Not (mypelanggan.Save()) Then MessageBox.Show("Gagal Backup SystemData ..!", "Ada Kesalahan", MessageBoxButtons.OK, MessageBoxIcon.Error)

End Sub