php - how to query one column by id in sql -

i wondering if figure query issue out. have googled around cannot find looking. hope can explain here.

i have products table contains, categoryid, productid, , imagefile columns.

i trying create function in can put variable images connects specific category id.

this function have far.

function get_image_by_category($category_id) {     global $db;     $query = 'select * products               products.imagefile = :category_id';     $statement = $db->prepare($query);     $statement->bindvalue(":category_id", $category_id);     $statement->execute();     $category_image = $statement->fetchall();     $statement->closecursor();     return $category_image; } 

i m using var_dump , comes null , array size 0;

this code use function in index image.

if ($action == 'list_products') {     $category_id = filter_input(input_get, 'category_id',              filter_validate_int);     if ($category_id == null || $category_id == false) {         $category_id = 1;     }     $categories = get_categories();     $category_image = get_image_by_category($category_id);       var_dump($category_image);  } 

please let me know if need more info.

thanks!

your query says this:

select * products products.imagefile = :category_id 

it doesn't make sense compare image file name category id. never come out equal.

also, you're using select *. pro tip: don't in software; instead name columns want returned.

try query instead:

select imagefile products category_id = :category_id 

if have lots of images each category , want them in single string comma separated, try this.

select group_concat(imagefile) images products category_id = :category_id