If I know the accountId of a record I can do something like this:

```
 Dim cols As New ColumnSet(New String() {"name",
                                         "address1_postalcode",
                                         "lastusedincampaign"})
 Dim retrievedAccount As Account = _orgService.Retrieve("account", _accountId, cols).ToEntity(Of Account)()

```

But what if I don't know the accountId and instead want to search for a record based on some other factor? Say, returning all records with "John" as the first name?