anyone get the promblem..

Anon

Does anyoine get the problme that they create a table with a primary key that is auto-incrementing. Then use a PHP script to add info to it.

But say the delete a record. Say, number 33
out of 40
So now you have 1 - 32 and 34 - 40
Now if you add another piece of data the next record is 41. How do you overcome this.

yelvington

Why is this a problem?

[deleted]

You don't, because this is exactly what auto_increment is for.
Auto_increment is used to make sure that you always get a unique number, and never a number that has already been used.

Auto_increment columns are meant to allow you to identify your records and make sure that whenever you ask for record with id=6, you allways get the right record.

If the numbers were re-used, then id=5 might mean record X today, and record Z tomorrow.

Anon

Okay, what i do is delete all entries,

then if i add a entry and look at the id, it will say 93 (at the moment,) if i delete that....and make another 94

[deleted]

And your question is...?

Anon

I was just stating that

[deleted]

Anon

Drop and recreate the table if you want to initialize the counter.

[deleted]

or read the manual:

-- quote --
When you add an AUTO_INCREMENT column, column values are filled in with sequence numbers for you automatically. You can set the first sequence number by
executing SET INSERT_ID=# before ALTER TABLE or using the AUTO_INCREMENT = # table option. See section 7.33 SET Syntax.
-- end quote --

smarlowe

But remember, you are now doing something database specific. Many other SQL databases have very different rules about autoincrementing fields. some allow you to insert an exact number out of sequence, assuming of course it isn't in use, but don't reset the counter (postgresl for example) while other dbms engines will not even let you put in your own number, period.

If you want your app to be portable, avoid relying on these quirky methods that change from dbms to dbms.

Anon

i am "still" new to PHP, have been "new" for about six months now. by the time i become a "veteran" PHP won't be in demand anymore.

what i don't understand is this, based on what the orignator of this message body was saying:

if you write code to display records #10 - #15, but record #10 does NOT exist, then how do you overcome this?

gumstic

Anon

Then you've written your code wrong. The way to display a range of records is to use a select statement with an order by and a limit/offset pair of keywords.

So, you'd have something like this:

select * from table order by something limit 10 offset 200;

to get the 200 through 209th row of a table.

Anon

Sorry if that sounded harsh, I was just in a hurry to get out the door.

I meant to add that the main reason for an autoincrementing id field, that may be part of a primary key, is to ensure a unique number for each member of a set, and the fact that they run sequentially doesn't mean that they don't have holes.

The other use, of course, is indexing for fast joins/unions etc...

There are a couple of real nice articles here on phpbuilder on doing just this thing that are VERY nicely done.