Question

say in mysql I have a column that’s id, just int auto increment.

Is there any way I can use php to tell me when there is an id that’s been removed?

Like say i have

5
6
7
8
10

I need it to tell me that the 9 is missing, and continue this for all the id’s. Is there any way to do this?

Thanks

Answer 1

You need a table that contains all values. Then it’s simple to do a left join to find missing ids.

create table all_values
(id int not null) engine = myisam;

insert into all_values (id) values (1),(2),(3),(4),(5),(6),(7),(8),(9),(10);

create table existing_values like all_values;

insert into existing_values (id) values (5),(6),(7),(8),(10);

select a.id from all_values as a
left join existing_values as b
on a.id = b.id
where b.id is null