Public Function CompanyNameExists(ByVal companyName As String) As Boolean
Dim query As String = "SELECT Count(*) FROM [yourtable] WHERE CompanyName=@CompanyName"
Dim rowCount As Integer
Using conn As New SqlConnection("your sql connection string")
conn.Open()
Using comm As New SqlCommand(query, conn)
comm.Parameters.AddWithValue("@CompanyName", companyName)
rowCount = Convert.ToInt32(comm.ExecuteScalar())
End Using
End Using
Return (rowCount > 0)
End Function