I want to find all unique records in the Dat1 field, but I want every single Null record returned. It doesn't matter which duplicate record is dropped. 

Example Table:

```
+----+--------------+
| ID |     Dat1     |
+----+--------------+
|  1 | 11@email.com |
|  2 | 11@email.com |
|  3 | NULL         |
|  4 | NULL         |
|  5 | 99@email.com |
|  6 | 99@email.com |
+----+--------------+

```

Desired Result:

```
+----+--------------+
| ID |     Dat1     |
+----+--------------+
|  1 | 11@email.com |
|  3 | NULL         |
|  4 | NULL         |
|  5 | 99@email.com |
+----+--------------+

```

Is this possible? I tried a couple of approaches with sub-queries but couldn't quite pull it off.