check the inserted value in text Box is available in sql server database or not

See more:

VB

Hello,
this is my code

con = New SqlConnection("Data Source=LOCALhost;Initial Catalog=InwardOutwardSystem;Integrated Security=True")
        con.Open()
        Dim T As String
        Dim x As String
        x = "select LoginId from UserMaster"
        
        If CBFrom.Text = x Then
            T = "insert into TransactionMaster(TransactionType)values=('Inward') "
        Else
            T = "insert into TransactionMaster(TransactionType)values('OutsideInward')"
        End If
        cmd = New SqlCommand(T, con)
        DR = cmd.ExecuteReader(CommandBehavior.CloseConnection)

In this
UserMaster is a Table in that LoginId field the employes name is resigter already

and i want to check that "CBFrom.Text" this is my application From TextBox name.
in if condition i m check the TextBox value is match with the UserMaster Table value or not.
if it will be matched then execute the 1st statement
otherwise execute the else statement.
But bt not work.
plz tell me what is wrong in this.