Syntax error (missing operator) in query expression 'Prod_Num =' - vb.net

Question

This Syntax error (missing operator) in query expression 'Prod_Num ='. always shows up when I'm trying to search an item in the database. Please help me.
Imports System
Imports System.Data
Imports System.Data.OleDb
Public Class Form1
Dim con As New OleDb.OleDbConnection
Dim cmd As OleDbCommand
Dim da As OleDb.OleDbDataAdapter
Dim ds As New DataSet
Dim dt As New DataTable
Dim sql As String
Dim dbp As String
Dim dbs As String
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
dbp = "Provider = Microsoft.ACE.OLEDB.12.0;"
dbs = "Data Source=" & Application.StartupPath & "/POS.accdb"
con.ConnectionString = dbp & dbs
con.ConnectionString = dbp & dbs
con.Open()
sql = "SELECT * FROM tblInventory"
da = New OleDb.OleDbDataAdapter(sql, con)
da.Fill(dt)
dgList.DataSource = dt
txtPNum.Focus()
End Sub
Private Sub btnSearch_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnSearch.Click
dt.Clear()
txtPNum.Text = ""
sql = "SELECT * FROM tblInventory WHERE Prod_Num =" & txtPNum.Text
da = New OleDb.OleDbDataAdapter(sql, con)
da.Fill(dt)
dgList.DataSource = dt
txtPName = dt.Rows(0).Item(1)
txtNOrder = dt.Rows(0).Item(2)
txtPRem = dt.Rows(0).Item(3)
txtPrice = dt.Rows(0).Item(4)
txtPNum.Focus()
End Sub

Answer 1

My guess is that you have problem here:
Private Sub btnSearch_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnSearch.Click
dt.Clear()
txtPNum.Text = "" ' <-----------------
sql = "SELECT * FROM tblInventory WHERE Prod_Num =" & txtPNum.Text
da = New OleDb.OleDbDataAdapter(sql, con)
da.Fill(dt)
dgList.DataSource = dt
txtPName = dt.Rows(0).Item(1)
txtNOrder = dt.Rows(0).Item(2)
txtPRem = dt.Rows(0).Item(3)
txtPrice = dt.Rows(0).Item(4)
txtPNum.Focus()
End Sub
Remove this line:
txtPNum.Text = ""
Since you always clears the txtPNum textbox's text before passing it to the query.
NOTE:
Don't forget to implement it via parameterized query. This is not a good approach.
See parameterized query examples:
Example 1
Example 2
Hope it helps!

Answer 2

does txtPNum.Text contain any data?
Why don't you try checking that, because if it is empty your running SQL statement is "SELECT * FROM tblInventory WHERE Prod_Num =" which would raise that error.
Also if the Prod_Num column is integer, perhaps you should use int(txtPNum.Text) if that value is a string, this would also prevent SQL Injection.

Answer 3

In addition to the problem with txtPNum.Text that others have pointed out, I would recommend a couple of other things:
Use parameterized queries to avoid SQL Injection.
Use Using blocks with your connection, and close the connection as soon as you are done. In your Form_Load, for example, you open the connection and leave it open. That is not good practice.
Example:
Imports System
Imports System.Data
Imports System.Data.OleDb
Public Class Form1
Dim con As OleDbConnection
Dim cmd As OleDbCommand
Dim da As OleDbDataAdapter
Dim ds As New DataSet
Dim dt As New DataTable
Dim dbp As String
Dim dbs As String
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
dbp = "Provider = Microsoft.ACE.OLEDB.12.0;"
dbs = "Data Source=" & Application.StartupPath & "/POS.accdb"
Using con As OleDbConnection = New OleDbConnection(dbp & dbs)
con.Open()
da = New OleDbDataAdapter("SELECT * FROM tblInventory", con)
da.Fill(dt)
dgList.DataSource = dt
End Using
txtPNum.Focus()
End Sub
Private Sub btnSearch_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnSearch.Click
dt.Clear()
Using con As OleDbConnection = New OleDbConnection(dbp & dbs)
con.Open()
da = New OleDbDataAdapter("SELECT * FROM tblInventory WHERE Prod_Num = #ProdNum", con)
da.SelectCommand.Parameters.AddWithValue("#ProdNum", txtPNum.Text)
da.Fill(dt)
dgList.DataSource = dt
End Using
txtPName = dt.Rows(0).Item(1)
txtNOrder = dt.Rows(0).Item(2)
txtPRem = dt.Rows(0).Item(3)
txtPrice = dt.Rows(0).Item(4)
txtPNum.Focus()
End Sub
I would also recommend adding some Try Catch blocks to handle errors, and you may need to convert the values you're assigning to text boxes if they're something other than String.