It's a low-tech solution but you could:
begin
update t1 set seq=-1 where id=5
update t1 set seq=5 where id=4
update t1 set seq=4 where id=-1
end
This is assuming that you don't naturally have -1 as a valid value of
that column.
chester c young wrote:
table t1:
id integer primary key,
seq integer not null unique
the seq is for ordering the rows as the user likes. however, if the
rows are moved around, eg
begin
update t1 set seq=4 where id=5
update t1 set seq=5 where id=4
end
will bomb because the first update has two rows of seq=4 (although
correct after the transaction).
I thought "deferrable initally deferred" would fix this, but the phrase
is not allowed on unique.
is this correct? any ideas?
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