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POVisual C# OleDbException when using variable in SQL WHERE clause
 

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    <p>Im currently using C# in visual studio and am using an access database. Im attempting to bring back data from a database when a customer is selected from a list box. This works perfectly when the sql is hard coded in e.g.</p> <pre><code>command.CommandText = "SELECT * FROM Customers WHERE CustomerID = 2 "; </code></pre> <p>However when I attempt to use a String variable to store the selected user ID I receive a "Data type mismatch in criteria expression" on the </p> <pre><code>"OleDbDataReader reader = command.ExecuteReader();". </code></pre> <p>I have used message boxes to confirm that the s2 variable contains the correct ID when chosen so I am unsure of the problem.</p> <p>Does anyone know a solution to this problem?</p> <pre><code> private void lst_disp_SelectedIndexChanged(object sender, EventArgs e) { String s = (String)lst_disp.SelectedItem; // the s string contains the selected customers ID + name, string s2 = s.Split(' ').FirstOrDefault(); // by spliting we can gain only the ID and store in s2 MessageBox.Show("Selected " + s2); showCust(s2); } private void showCust(string s2) { dataGridView1.AllowUserToAddRows = false; dataGridView1.Columns.Add("CustomerID", "Customer ID"); dataGridView1.Columns.Add("CustomerName", "Customer Name"); dataGridView1.Columns.Add("Description", "Description"); dataGridView1.Columns.Add("Email", "Email"); dataGridView1.Columns.Add("Telephone", "Telephone"); dataGridView1.Columns.Add("DeliveryAddress", "Delivery Address"); dataGridView1.Columns.Add("Notes", "Notes"); OleDbConnection connect = new OleDbConnection(); connect.ConnectionString = @"Provider=Microsoft.ACE.OLEDB.12.0;Data Source=E:\Uni\Year 3\Final Year Project\independent foods\coding\showCustomers\Database1.accdb;Persist Security Info=False"; connect.Open(); MessageBox.Show("Connection open"); OleDbCommand command = new OleDbCommand(); command.Connection = connect; MessageBox.Show("SELECT * FROM Customers WHERE CustomerID = '" + s2 + "' "); command.CommandText = "SELECT * FROM Customers WHERE CustomerID = '" + s2 + "' "; try { OleDbDataReader reader = command.ExecuteReader(); while (reader.Read()) { dataGridView1.Rows[dataGridView1.Rows.Count - 1].Cells["CustomerID"].Value = reader[0].ToString(); dataGridView1.Rows[dataGridView1.Rows.Count - 1].Cells["CustomerName"].Value = reader[1].ToString(); dataGridView1.Rows[dataGridView1.Rows.Count - 1].Cells["Description"].Value = reader[2].ToString(); dataGridView1.Rows[dataGridView1.Rows.Count - 1].Cells["Email"].Value = reader[3].ToString(); dataGridView1.Rows[dataGridView1.Rows.Count - 1].Cells["Telephone"].Value = reader[4].ToString(); dataGridView1.Rows[dataGridView1.Rows.Count - 1].Cells["DeliveryAddress"].Value = reader[5].ToString(); dataGridView1.Rows[dataGridView1.Rows.Count - 1].Cells["Notes"].Value = reader[6].ToString(); } } catch(Exception e) { MessageBox.Show("The File cann't be read. Error: " + e.Message); } } </code></pre>
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    1. USMark Taylforth
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      1. USJohn Saunders
 

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