You could write it as
$query->execute() or do { $SQL_FAIL = 1};
But for a single line statement, you really don't need the braces, just :
$query->execute() or $SQL_FAIL = 1;
But why are you doing it this way?
This means that you then have to check the value of SQL_FAIL every line before processing the next statement.
Wrapping it all in an eval and using RaiseError really works a treat, looks clean makes your life simpler.
If you are using the value of SQL_FAIL to figure out what statement failed, then you could go the other way and have $sql_stage (note, not all in capitals because this implies a constant, which it isn't) and you could just set $sql_stage to the current stage you're working on. As in
my $sql_stage=1;
eval {
$query->execute();
$sql_stage = 2;
$query2->execute();
$sql_stage = 3;
$query3->execute();
};
if ($@) {
if ($sql_stage < 3) {
$fix1->execute();
} else {
$fix2->execute();
}
}