how to retrive next id

[okazu]

Which is the beter way to retrieve from a table the next primary key id which is NOT using auto-incremented?

- use something like "select max(id)"

- use another sequential table (which is common in most of the database abstraction layer scripts)

thanks in advance

[Defender1]

Well, if your making id's that always go up sequentially, you can use max. And it'll take the largest number.
Or you could just sort them with order by column_name DESC and it'll sort the numbers starting with the highest. so just take the first entry that your query returns ant that'll be the highest id.

[okazu]

Yes, I think that's the easiest way, but why do most of the abstract database layer scripts use another sequential table for this?
I know that if you use a sequential table, you will not reuse a deleted id, which helps avoiding data relation inconsistencies, but is this the only reason they use the sequential table? Doesnt that affect the performance?