Question

i am very new to PHP and MySQL. I am trying to write a php script and i am stucking with the selection of rows from a table

The code that works great is:

$q_pages = $wpdb -> prefix . 'q_pages_table';

$q_kws = $wpdb->prefix . 'q_kws_table';

$sql = 'SELECT a1.post_id, a1.kw_id, a2.kw_name ' +
       'FROM ' . $q_pages . ' as a1 ' +
       'LEFT JOIN ' . $q_kws . ' as a2 ON (a1.kw_id = a2.id)' + 
       'WHERE a1.draft_id = 4';

The third command is to select and join columns from variable $q_kws to variable $q_pages if there is a match between kw_id and id in the 2 tables and also when the draft_id = 4

Because of the large number of rows in the $sql variable (3000 rows), i want to break $sql to 3 variables, each variable contains 1000 rows, so that later i can process each variable separately.

Is there any suggestion?

Thank you

Answer 1

You can use limit in the query to retrieve a specific number of rows .

something like 
$start=0;
$end=1000;

$sql = 'SELECT a1.post_id, a1.kw_id, a2.kw_name ' +
       'FROM ' . $q_pages . ' as a1 ' +
       'LEFT JOIN ' . $q_kws . ' as a2 ON (a1.kw_id = a2.id)' + 
       'WHERE a1.draft_id = 4 limit ".$start.",".$end."';