Help with Joins

[m3avrck]

Hi everyone. I'm new to mySQL but I understand the basics.

I'm just wondering how I would go about the following:

Lookup value from table1 and then retrieve all values in table2 that have the ID from the table1 value that is selected

I think I need to join like the following:

$query= 'SELECT `errorname` FROM `level0` LEFT JOIN `level1` ON `level0ID`=`level1ID`';

But for some reason I'm getting "Column: 'errorname' in field list is ambiguous" ...any ideas? Here are what my tables look like:

+----------+-----------+-----------+------------+-----------+
| level0ID | tibetName | errorName | tibetReady | validated |
+----------+-----------+-----------+------------+-----------+
|        4 | AA        | AA        |          0 |         0 |
|        5 | BB        | BB        |          0 |         0 |
|        6 | CC        | CC        |          0 |         0 |
|        7 | DD        | DD        |          0 |         0 |
+----------+-----------+-----------+------------+-----------+

+----------+-----------+-----------+------------+-----------+----------+
| level1ID | tibetName | errorName | tibetReady | validated | level0ID |
+----------+-----------+-----------+------------+-----------+----------+
|        5 | aa        | aa        |       NULL |      NULL |        4 |
|        7 | cc        | cc        |       NULL |      NULL |        6 |
|        6 | bb        | bb        |       NULL |      NULL |        5 |
|        8 | dd        | dd        |       NULL |      NULL |        7 |
|        9 | no        | no        |       NULL |      NULL |        0 |
+----------+-----------+-----------+------------+-----------+----------+

Basically all I want to do, is if the user selected level0ID=4, I want to show all level1's who have level0ID=4.

Thanks.

[m3avrck]

I did manage to get this to work:

$query= "SELECT `level0ID` FROM `level0` WHERE `errorName`='$s'";
  $result= dbQuery($query);
  $num= mysql_fetch_row($result);
   
  $query= "SELECT `errorName` FROM `level1` WHERE `level0ID`='$num[0]'";
  $result= dbQuery($query); 

But I am assuming I could have done this with a JOIN or something. But I can't get this to work at all. Maybe my database is messed up using the same names in each table. Any ideas?

[beetle]

SELECT l1.errorName 
FROM level0 l0, level1 l1
WHERE l1.level0ID = l0.level0ID
GROUP BY l1.errorName