SQL questions

I have table "lists" with columns "id" (key) and "container" which implement
a connected list like that:
id | container
1 | NULL
2 | 1
3 | NULL
4 | 1
5 | 6
6 | 4
7 | 4
8 | 7

is there a query to get the whole list in one row until it find NULL like
that???
1 NULL
2 1 NULL
3 NULL
4 1 NULL
5 6 4 1 NULL
6 4 1 NULL
7 4 1 NULL
8 7 4 1 NULL

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We suppose now that we JOIN upper table "lists" with table "strings" ON
lists.id = strings.id
Table "strings" has columns "id" (key), "language" (key) and "string" like
this:
id | language | string
1 | english | OpenGL
1 | german | [NULL]
2 | english | Java
2 | german | [NULL]
3 | english | News
3 | german | Nachrichten

I want a query which when german "language" has "string" NULL return english
"language"
I construct something like this but it is incomplete:

SELECT lists.id, container, IFNULL(a.string, 'What I must give here?????')
FROM lists JOIN strings ON lists.id=strings.id WHERE language=<something>