mysql - Writing a PDO search query from a PHP array -

i'm building application using php 7 , pdo connection mysql database.

one part of application contains search form allows user search training course 3 different fields: course category, course name, , date.

the types of elements on form are:

1. course category - dropdown, numerical (int) id's.
2. course name - text input
3. date - date picker (using html 5 type="date" parameter calendar in browser).

these fields can used in conjunction, or on own. means user search, example, (1), or (2 & 3), or (1 & 2 & 3).

i've written php post data , it's in array - example:

$search_data = [     'category' => 3,     'name' => 'hazard training',     'date' => '' ] 

i want use within pdo query don't know best way write because (1) , (3) = query condition, whereas (2) like. solution going looping through search terms , trying construct query, e.g.

$sql = ' '; foreach ($search_data $key => $value) {     if ($key == 'category') {         $sql .= ' category = ' . $value;     }     if ($key == 'course_name') {         $sql .= ' course_name % ' . $value ' % ';     }     if ($key == 'date') {         $sql .= ' date = ' . $value;     } } 

the trouble doesn't work because of having bind parameters in pdo. doesn't work because can't find way and between each query (if there preceding statement).

i'm lost , unsure best way write is.

any appreciated.

edit: realise hardcoding names, e.g. ($key == 'course_name') isn't ideal, being done because of different query conditions (like vs =). assume 1 make $search_data multi-dimensional type of query was, beyond initial problem , post.

here`s simple solution problem:

$sql = 'select ..... ... 1 '; $where = ''; $pdodata = [];  foreach ($search_data $key => $value) {     if(!$value) continue; // skip empty values      if ($key === 'category') {         $pdodata[':category'] = $value;         $where .= ' , category = :category ';     }     if ($key === 'course_name') {         $pdodata[':course_name'] = '%'.$value.'%';         $where .= ' , course_name (:course_name) ';     }     if ($key === 'date') {         $pdodata[':date'] = $value;         $where .= ' , date = :date ';     } }  $sql = $sql.$where;  $stmt = $this->ci->db->prepare($sql); $stmt->execute($pdodata); $results = $stmt->fetchall(pdo::fetch_assoc); 

and have $pdodate array holding binded data.