Dynamic Sql - retrieve from Oracle - vb.net

Question

I have a form with button which should find records from Oracle database. I have three Textboxes on same form, and If text matches with values in fields of DB, Datagrid should show me this records. Here is my code:
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
'connect to oracle DB
Dim oradb As String = "Data Source=orcl;User Id=Lucky;Password=Example;"
Dim conn As New OracleConnection(oradb)
conn.Open()
Dim SQL As String
SQL = "SELECT * FROM MyTable WHERE 1=1"
'SQL statement for 1st textbox
If Not TxtName.Text = "" Then
SQL = SQL & " AND USER_NAME =" & TxtName.Text
End If
'SQL statement for 2nd textbox
If Not TxtSurname.Text = "" Then
SQL = SQL & " AND USER_SURNAME =" & TxtSurname.Text
End If
'SQL statement for 3rd textbox
If Not TxtAddress.Text = "" Then
SQL = SQL & " AND USER_ADDRESS=" & TxtAddress.Text
End If
'select SQL statements and retrieve data using ExecuteReader
Dim cmd As New OracleCommand(SQL, conn)
cmd.CommandType = CommandType.Text
Dim dr As OracleDataReader = cmd.ExecuteReader()
Dim dt As New DataTable
dt.Load(dr)
DataGridView1.DataSource = dt
End Sub
What am I doing wrong, nothing happens when button clicked?

Answer 1

This is a non-tested sample of the direction you could try:
Private Sub populateDataGridView()
'connect to oracle DB
Const connectionString As String = "Data Source=orcl;User Id=Lucky;Password=Example;"
Using conn As New OracleConnection(connectionString)
conn.Open()
Using cmd As New OracleCommand()
Dim SQL As String = "SELECT * FROM testtable "
Dim conjunction As String = " Where "
'SQL statement for 1st textbox
If Not TxtName.Text.Length = 0 Then
SQL = String.Concat(SQL, conjunction, " USER_NAME like :username")
cmd.Parameters.Add(New OracleParameter("username", String.Concat("%", TxtName.Text, "%")))
conjunction = " and "
End If
'SQL statement for 2nd textbox
If Not TxtSurname.Text.Length = 0 Then
SQL = String.Concat(SQL, conjunction, " user_surname like :usersurname")
cmd.Parameters.Add(New OracleParameter("usersurname", String.Concat("%", TxtSurname2.Text, "%")))
conjunction = " and "
End If
'SQL statement for 3rd textbox
If Not TxtAddress.Text.Length = 0 Then
SQL = String.Concat(SQL, conjunction, " user_address like :useraddress")
cmd.Parameters.Add(New OracleParameter("useraddress", String.Concat("%", TxtAddress.Text, "%")))
End If
'select SQL statements and retrieve data using ExecuteReader
cmd.Connection = conn
cmd.CommandText = SQL
cmd.CommandType = CommandType.Text
Dim dr As OracleDataReader = cmd.ExecuteReader()
Dim dt As New DataTable
dt.Load(dr)
DataGridView1.DataSource = dt
End Using
End Using
End Sub