I seem to be thinking wrong today. I have two tables as follows

```
+--------+  +------------------------+
|person  |  |contact                 |
+--------+  +-----------------+------+
|id |name|  |person_id |type  | value|
+--------+  +------------------------+
|00 |a   |  |00        |phone |123   |
|01 |b   |  |00        |email |a@a.a |
|02 |c   |  |01        |phone |456   |
|03 |d   |  |02        |email |c@c.c |
+--------+  +------------------------+

```

and I need **all** persons and **optionally** their phone number, e.g.

```
+-----------+
|name |phone|
+-----------+
|a    |123  |
|b    |456  |
|c    |     |
|d    |     |
+-----+-----+

```