VB.net / SQL Adding Data - sql-server

Question

My question is somewhat complex but simple. I am building a small program to keep track of inventory. I created a view that contains a list of names and id in SQL. I then created a table so that I can add items to the names in SQL
IN vb.net
When the users clicks on the 1st datagridview - the name and number comes in separate text boxes. When they click the save button the records will then get saved to my table. (Which I have another Datagridview to show names and items. ) When I click my save button I get the following error:
Violation of PRIMARY KEY constraint 'PK_Inventory_Detail'. Cannot insert duplicate key in object 'dbo.Inventory_Detail'. The duplicate key value is (4 ).
I initially had the foreign key but then dropped based on the error but I am still getting it????
Imports System.Data.SqlClient
Public Class Form1
Dim cn As New SqlConnection("Data Source=;Initial Catalog=Inventory;User ID=;Password=")
Dim adap As New SqlDataAdapter("SELECT res_snbr, res_First_Name, res_Last_Name FROM ResidentInventoryView", cn)
Dim builder As New SqlCommandBuilder(adap)
Dim dt As New DataTable
Dim res_snbr As Object
'Dim InventoryDetailsBindingSource As New BindingSource
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles Me.Load
' DataGridView1.AllowUserToAddRows = True
' DataGridView1.AllowUserToDeleteRows = True
DataGridView1.[ReadOnly] = False
'
adap.Fill(dt)
ResidentInventoryViewBindingSource.DataSource = dt
DataGridView1.DataSource = ResidentInventoryViewBindingSource
End Sub
Private Sub TextBox1_TextChanged(sender As Object, e As EventArgs) Handles TextBox1.TextChanged
If TextBox1.TextLength > 0 Then
ResidentInventoryViewBindingSource.Filter = String.Format("res_First_Name Like '%{0}%'", TextBox1.Text)
Else
ResidentInventoryViewBindingSource.Filter = String.Empty
End If
End Sub
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
Try
adap.Update(dt)
MessageBox.Show("Saved successfully")
Catch ex As Exception
MessageBox.Show("Error updating database")
End Try
End Sub
Private Sub DataGridView1_CellContentClick(sender As Object, e As DataGridViewCellEventArgs) Handles DataGridView1.CellContentClick
Dim i As Integer
i = DataGridView1.CurrentRow.Index
Me.rlastname.Text = DataGridView1.Item(0, i).Value
Me.rfname.Text = DataGridView1.Item(1, i).Value
Me.rnum.Text = DataGridView1.Item(2, i).Value
End Sub
Private Sub Button2_Click(sender As Object, e As EventArgs) Handles Button2.Click
cn.Open()
Dim cmd As New SqlCommand(("Insert INTO Inventory_Detail Values('" & _
rnum.Text & "','" & _
rfname.Text & "','" & _
rnum.Text & "','" & _
txtitem.Text & "','" & _
"" & "','" & _
"" & "')"), cn)
cmd.ExecuteNonQuery()
cn.Close()
MsgBox("Success....", MsgBoxStyle.Information, "Success")
rnum.Clear()
rfname.Clear()
rnum.Clear()
txtitem.Clear()
End Sub
End Class

Answer 1

You already have an item in the Inventory_Detail table with the id of 4. You need to increment the id so that every record in the Inventory_Detail table has a unique id.
You can you the Identity property in SQL to Increment your Primary Key so you don't have to insert the id manually.
Identity MSDN
Or Consider using a GUID that way it is always unique.

Answer 2

Right, so what I did ( maybe not the best)
created a view to get all names and ids
Created one table - contains a primary key that auto Increments
has an id field
item
start date
end date
The above will allow one person to be assigned multiple items and keep track of the items