[Solved] mysql subquery in large insert query

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mysql subquery in large insert query

Database type:

I need to make a subquery in a large query, but am unsure on how to implement this with many other predefined values involved. Lots of examples just show 2 rows that are both obtained trough the subquery.

Can anyone explain to me how to check for the last 'ordernummer' add that with +1 and use that value in the insert query?

INSERT INTO orderheaders (user, timestamp, ipadres, ordernummer, ordernummer_cash, offertenummer, debnr, contact, referentie, quantity, totaal, paymethod, shipmethod, paymentkey, bank_id) 
VALUES ('".$user."', '".time()."', '".$_SERVER['REMOTE_ADDR']."', '".$ordernummer."',$ordernummer,'".$_POST['offertenummer']."','".$newdeb."', '".$newcontact."', '".$_POST['referentie']."', '".$total_qty_prods."', '".$totaal."', '".$paymethod."', '".$shipping."', '".$paymentkey."', '')

so for $ordernummer I need to get the value of 

SELECT ordernummer FROM orderheaders ORDER BY id DESC LIMIT 0,1

How to optimize this SQL query?

The following recommendations will help you in your SQL tuning process.
You'll find 3 sections below:

  1. Description of the steps you can take to speed up the query.
  2. The optimal indexes for this query, which you can copy and create in your database.
  3. An automatically re-written query you can copy and execute in your database.
The optimization process and recommendations:
  1. Avoid OFFSET In LIMIT Clause (query line: 6): OFFSET clauses can be very slow when used with high offsets (e.g. with high page numbers when implementing paging). Instead, use the following \u003ca target\u003d"_blank" href\u003d"http://www.eversql.com/faster-pagination-in-mysql-why-order-by-with-limit-and-offset-is-slow/"\u003eseek method\u003c/a\u003e, which provides better and more stable response rates.
  2. Create Optimal Indexes (modified query below): The recommended indexes are an integral part of this optimization effort and should be created before testing the execution duration of the optimized query.
Optimal indexes for this query:
ALTER TABLE `orderheaders` ADD INDEX `orderheaders_idx_id` (`id`);
The optimized query:
SELECT
        orderheaders.ordernummer 
    FROM
        orderheaders 
    ORDER BY
        orderheaders.id DESC LIMIT 0,
        1

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* original question posted on StackOverflow here.