Getting total rows using Drupal 7 Database API when using limit - mysql

Question

I am using the Drupal 7 Database API to search my table. I am also using the paging and sorting extenders. So the problem is, how do I display the total number of records found when my query is using limit because of the pagination? Do I need to run my query that has all of the conditions TWICE? Once to get the count and another one with the limit? That seems inefficient. Here is my code for reference. I am new to the Database API so feel free to adjust my code or point me in the right direction if I'm doing something wrong. Also I'm not done with this yet and only have one condition in place, but I will end up having 3. THANKS:
function job_search() {
// Initialising output
$output = 'SOME STUFF';
// Table header
$header = array(
array('data' => 'Description'),
array('data' => 'Location', 'field' => 'job_location_display'),
array('data' => 'Specialty', 'field' => 'specialty_description'),
array('data' => 'Job Type', 'field' => 'job_board_type'),
array('data' => 'Job Number', 'field' => 'job_number'),
);
// Setting the sort conditions
if(isset($_GET['sort']) && isset($_GET['order'])) {
// Sort it Ascending or Descending?
if($_GET['sort'] == 'asc')
$sort = 'ASC';
else
$sort = 'DESC';
// Which column will be sorted
switch($_GET['order']) {
case 'Location':
$order = 'job_location_display';
break;
case 'Specialty':
$order = 'specialty_description';
break;
case 'Job Number':
$order = 'job_number';
break;
case 'Job Type':
$order = 'job_board_type';
break;
default:
$order = 'job_number';
}
}
else {
$sort = 'ASC';
$order = 'job_number';
}
// Query object
$query = db_select("jobs", "j");
// Adding fields
$query->fields('j');
if(isset($_GET['location'])) {
$query->condition('j.job_state_code', $_GET['location'], '=');
}
// Set order by
$query->orderBy($order, $sort);
// Pagination
$query = $query->extend('TableSort')->extend('PagerDefault')->limit(20);
// Executing query
$result = $query->execute();
// Looping for filling the table rows
while($data = $result->fetchObject()) {
$description = '<div class="thumbnail"><img src="/sites/all/themes/zen/vista_assets/images/job_headers/' . $data->job_image_file . '"/></div>';
$description .= '<div class="title">' . $data->job_board_subtitle . '</div>';
// Adding the rows
$rows[] = array($description, $data->job_location_display, $data->specialty_description, $data->job_board_type, $data->job_number);
}
$output .= theme('pager');
// Setting the output of the field
$output .= theme_table(
array(
'header' => $header,
'rows' => $rows,
'attributes' => array('id' => array('job-listing')),
'sticky' => true,
'caption' => '',
'colgroups' => array(),
'empty' => t("No records found.")
)
).theme('pager');
// Returning the output
return $output;
}
This ended up working:
//get total records
$num_rows = $query->countQuery()->execute()->fetchField();
// add paging and sorting
$query = $query->extend('TableSort')->extend('PagerDefault')->limit(20);
//execute again
$result = $query->execute();

Answer 1

According to the documentation:https://api.drupal.org/api/drupal/includes!database!database.inc/function/db_query/7
in order to get the total number of rows it is better to use db_query() function, cause it has the method rowCount() which returns total number of query rows:
<?php
// Using the same query from above...
$uid = 1;
$result = db_query('SELECT n.nid, n.title, n.created
FROM {node} n WHERE n.uid = :uid', array(':uid' => $uid));
// Fetch next row as a stdClass object.
$record = $result->fetchObject();
// Fetch next row as an associative array.
$record = $result->fetchAssoc();
// Fetch data from specific column from next row
// Defaults to first column if not specified as argument
$data = $result->fetchColumn(1); // Grabs the title from the next row
// Retrieve all records into an indexed array of stdClass objects.
$result->fetchAll();
// Retrieve all records as stdObjects into an associative array
// keyed by the field in the result specified.
// (in this example, the title of the node)
$result->fetchAllAssoc('title');
// Retrieve a 2-column result set as an associative array of field 1 => field 2.
$result->fetchAllKeyed();
// Also good to note that you can specify which two fields to use
// by specifying the column numbers for each field
$result->fetchAllKeyed(0,2); // would be nid => created
$result->fetchAllKeyed(1,0); // would be title => nid
// Retrieve a 1-column result set as one single array.
$result->fetchCol();
// Column number can be specified otherwise defaults to first column
$result->fetchCol($db_column_number);
// Count the number of rows
$result->rowCount();
?>