I'm facing an issue trying to join 4 tables:

**Conversation:** 

```
+-----+---------+------------+
| id: | start:  |    end:    |
+-----+---------+------------+
| a   |  3      |    87      |
| e   |  <null> |   4        |
| h   |  4      |    67      |
| l   |  5      |    6       |
| o   |  <null> |  <null>    |
+-----+---------+------------+

```

**Phone:** 

```
+-----+-------------+--------+
| id: | P_duration: | T_id:  |
+-----+-------------+--------+
| a   | 2           | a1     |
| e   | <null>      | <null> |
| h   | 5           | <null> |
+-----+-------------+--------+

```

**Chat:** 

```
+-----+--------------+---------+
| id: |  C_duration: |  T_id:  |
+-----+--------------+---------+
| l   |            4 |    a2   |
+-----+--------------+---------+

```

**Ticket** 

```
+---------+
|    T_id |
+---------+
|    a1   |
|    a2   |
|    a3   |
+---------+

```

What I'm trying to obtain is something like this:

**Result:** 

```
+--------+-------------+-------------+--------+
|  id:   | P_duration: | C_duration: | T_id:  |
+--------+-------------+-------------+--------+
| a      | 2           | <null>      | a1     |
| e      | <null>      | <null>      | <null> |
| h      | 5           | <null>      | <null> |
| l      | <null>      | 4           | a2     |
| o      | <null>      | <null>      | <null> |
| <null> | <null>      | <null>      | a3     |
+--------+-------------+-------------+--------+

```

I tried with a query like this

```
SELECT 
    conv.id, p.P_duration, c.C_duration, t.T_id
FROM 
    Conversations conv
LEFT JOIN 
    phone p ON p.id = conv.id
LEFT JOIN 
    chat c ON c.id = conv.id
LEFT JOIN 
    ticket t ON (t.T_id = p.T_id OR t.T_id = c.T_id)

```

Unfortunately this is not working since I can't cover the last row on the result table case: when I have a ticket but no conversation.

How should I change the query?

Thanks in advance