next / previous pagination query with parameters php mysql with parameters - php

Question

I have the following problem: here is the structure of my tables
and here is my code:
$SQL_NEXT_PROJECT_ID ="SELECT id FROM projects WHERE id < '".$id_project."' and project_types_id='".$project_type_id."' ORDER BY id DESC LIMIT 1";
$conn->query($SQL_NEXT_PROJECT_ID);
foreach ($conn->query($SQL_NEXT_PROJECT_ID) as $rowProjectNext) {
$next_project_id = $rowProjectNext['id'];
}
$SQL_PREVIOUS_PROJECT_ID ="SELECT id FROM projects WHERE id > '".$id_project."' and project_types_id='".$project_type_id."' ORDER BY id ASC LIMIT 1";
$conn->query($SQL_PREVIOUS_PROJECT_ID);
foreach ($conn->query($SQL_PREVIOUS_PROJECT_ID) as $rowProjectPrevious) {
$previous_project_id = $rowProjectPrevious['id'];
}
the thing is that i need to put the query with an aditional condition from the 'images' table i have to evaluate the main field ='1', i have been trying to do it with a inner join but it doesnt seem to work, here i attach the query that i have been trying
$SQL_NEXT_PROJECT_ID ="SELECT projects.id FROM projects INNER JOIN images WHERE projects.id > '".$id_project."' and project_types_id='1' and main='1' ORDER BY projects.id DESC LIMIT 1";
Basically what i need to do is to create next / previous links to projects of certain type (project_types_id) based on the current id of the project ($id_project) taking into consideration the fact that the project should have a image that has the main field equal to '1'
hope i explained myself well...

Answer 1

Well youre not joining on anything... you need an ON clause.
SELECT pr.id FROM projects pr
INNER JOIN images img ON (pr.id = img.projects_id AND img.main = 1)
WHERE pr.id > ?
AND pr.project_types_id = 1
ORDER BY pr.id DESC LIMIT 1

Answer 2

at the end i did it like this
$_nextPrevious = array();
$SQL_SEARCH_VALUES="SELECT images.projects_id AS projectId FROM projects INNER JOIN images ON ( projects.id = images.projects_id ) AND project_types_id = '".$project_type_id."' AND images.main = '1' LIMIT 0 , 30";
$conn->query($SQL_SEARCH_VALUES);
foreach($conn->query($SQL_SEARCH_VALUES) as $rowNextPrevious) {
$value = $rowNextPrevious['projectId'];
array_push($_nextPrevious, $value);
}
$currentValue = array_search($id_project, $_nextPrevious);
$next = $currentValue + 1;
$previous = $currentValue - 1;
$next_project_id = $_nextPrevious[$next];
$previous_project_id = $_nextPrevious[$previous];
return array($project_name,$project_description,$project_path, $_images, $next_project_id, $previous_project_id);
using an array instead of two searches...