before/after triggers

If I have a before trigger on table 'A' modify  table 'B' and an after trigger
on table 'A' fails for that transaction:

1/ Is the change to table 'B' visible to anybody except that tranaction at any time?

2/ Does the change to table 'B' disappear/never show up when the after trigger
fails?

3/ Would all after triggers in that transaction see the change to table 'B'
before the one particular after trigger fails?

4/ do all the major DB's have this functionality? I.E.

    Oracle
    Sybase
    MSSQL (yuck)
    DB2
    <other examples welcome>