I have made a small app where a table of data is presented to the user. The data can be sorted by different column headers and filter using inputs.
When the user clicks on a row it opens a small popup which contains two arrows for going to the next and previous record, in the same order as they appear in the table.
Originally I had (for "previous" as an e.g.):
SELECT ed.id
FROM entity_details AS ed, users
WHERE ed.id > ?
AND ed.typeRef = ?
AND ed.ownerRef = users.id
$filter
$SQLOrder LIMIT 1
Which works fine if the table is sorted by ed.id, but will not work properly if sorted by another column e.g. ed.name, because the next alphabetical name might have a much higher or lower id.
FYI $filter could be something like:
AND branchRef = 2
and $SQLOrder could be:
ORDER BY ed.name DESC
What do I need to do to make it cycle through the records properly, respecting current order and record position?
All the sorting and filtering parameters come through over AJAX, e.g:
$JSON->selectedbranch ;
I've come to the conclusion that all I need to know is how to start the query from a row with column X containing value Y, is that possible?
You should store the number of the row you displayed, not the ID. Then just do the ordering in SQL as your application requirements imply, then apply the knowledge contained here:
Skipping first n results in MySQL
To simplify the job, and to make this answer usable for future SO dwellers:
SELECT ed.id
FROM entity_details AS ed, users
WHERE ed.typeRef = ?
AND ed.ownerRef = users.id
$filter
$SQLOrder
LIMIT $currentRowNum,1
This scheme smells however: using this to navigate your rows implies a SQL query for each navigation action. That might have an bad effect on your response time...
PHP's mysql_data_seek function may helps.
I found it, seeing that other guys answer gave me an idea, but his answer has disappeared :(
For the next button I have:
$result = $dbh->prepare("SELECT ed.id
FROM entity_details AS ed, users
WHERE $WHERE < ?
AND ed.typeRef = ?
AND ed.ownerRef = users.id
$filter
ORDER BY ed.name DESC LIMIT 1") ;
$WHERE is just the column name "ed.name".
I just have to sort out the dynamics for $where and the ORDER BY clause and it'll be good to go.
Thanks for every ones input!