The parameterized query expects the parameter which was not supplied - sql

Question

I'm having a problem with my code:
Private Sub TextBox2_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles TextBox2.TextChanged
list.Items.Clear()
cmd.CommandText = "SELECT * FROM borrow where (Department LIKE '%" & TextBox2.Text & "%')"
cmd.Connection = con
cmd.CommandType = CommandType.Text
con.Open()
rd = cmd.ExecuteReader()
If rd.HasRows = True Then
While rd.Read()
Dim listview As New ListViewItem
listview.Text = rd("ID").ToString
listview.SubItems.Add(rd("Department").ToString)
listview.SubItems.Add(rd("Purpose").ToString)
listview.SubItems.Add(rd("Items_Details").ToString)
listview.SubItems.Add(rd("Requested_by").ToString)
listview.SubItems.Add(rd("Approved_by").ToString)
listview.SubItems.Add(rd("Date").ToString)
listview.SubItems.Add(rd("Status").ToString)
listview.SubItems.Add(rd("Date_Returned").ToString)
list.Items.Add(listview)
End While
End If
con.Close()
Once I typed in the string in the textbox to search for an item I get this error:
The parameterized query '(#Parameter1 nvarchar(4000))SELECT * FROM
borrow where (Departme' expects the parameter '#Parameter1', which was
not supplied.
Can anyone help me?

Answer 1

If you pass null value to parameter,you will get this error even after you add the parameter
so try to check the value and if it null then use DBNull.Value
This will work
cmd.Parameters.Add("#Department", SqlDbType.VarChar)
If (TextBox2.Text = Nothing) Then
cmd.Parameters("#Department").Value = DBNull.Value
Else
cmd.Parameters("#Department").Value = TextBox2.Text
End If
This will convert the null values from the object layer to DBNull values that are acceptable to the database.

Answer 2

Your website is in serious danger of being hacked.
Read up on SQL Injection and how to prevent it in .NET
Your query problem is the least of your concerns right now.
But.....
#Misnomer's solution is close but not quite there:
Change your query to this:
cmd.CommandText = "SELECT * FROM borrow where (Department LIKE '%#DepartmentText%')"
and add parameters this way (or the way that #Misnomer does):
cmd.Parameters.AddWithValue("#DepartmentText",TextBox2.Text)
The important difference is that you need to change your CommandText.

Answer 3

Building on and simplifying ravidev's answer:
The VB.NET shorthand is:
cmd.Parameters.AddWithValue("#Department", IF(TextBox2.Text, DBNull.Value))
The C# shorthand is:
cmd.Parameters.AddWithValue("#Department", (object)TextBox2.Text ?? DBNull.Value)

Answer 4

Try adding parameters like this -
cmd.Parameters.Add("#Department", SqlDbType.VarChar)
cmd.Parameters("#Department").Value = TextBox2.Text
and change your command text to what #Abe Miessler does he is right i just thought you will figure it out.

Answer 5

If you are writing from a DataGridView control to your database, make sure there is no empty row. Set 'Allow User to add Rows' to false; it truncates the unnecessary last empty row.

Answer 6

SqlConnection conn = new SqlConnection(connectionString);
conn.Open();
//SelectCustomerById(int x);
comboBoxEx1.Items.Clear();
SqlCommand comm = new SqlCommand("spSelectCustomerByID", conn);
//comm.Parameters.Add(new SqlParameter("cust_name", cust_name));
//comm.CommandText = "spSelectCustomerByID";
comm.Parameters.Add(new SqlParameter("cust_id", SqlDbType.Int));
comm.CommandType = CommandType.StoredProcedure;
comm.ExecuteNonQuery();
SqlDataAdapter sdap = new SqlDataAdapter(comm);
DataSet dset = new DataSet();
sdap.Fill(dset, "cust_registrations");
if (dset.Tables["cust_registrations"].Rows.Count > 0)
{
comboBoxEx1.Items.Add("cust_registrations").ToString();
}
comboBoxEx1.DataSource = dset;
comboBoxEx1.DisplayMember = "cust_name";