How to search for a multiple column in "where" clause which may be null sometimes but others should work if they aren't null

Question

I want to write a single query instead of "if" statements which should be able to fetch filter applied data

The columns passed in "where" clause are:

usedBy,item_type,item_rarity,item_slot

filters={"hero":"Axe","type":"Weapon","rarity":"rare","slot":"hand","title":"Blood Shed"}

In above json all filters are applied and no null value so the simple sql query works great,for example

Select * from table where usedBy = 'Axe' and item_type = 'weapon' and item_rarity='rare' and item_slot = 'hand' and item_title = 'Blood shed'

But if anyone of them is null i wont get any result. for example :

filters={"hero":"Axe","type":"","rarity":"","slot":"","title":""}

So I want a query which can handle both the above requests at the same time.

Tried queries are(variables are used):

SELECT usedBy,item_type,item_name,item_slot,item_rarity from descriptions where usedBy = '$hero' and item_type ='$type' or item_type = '' and item_rarity='$rarity' or item_rarity ='' and item_slot='$slot' or item_slot = '' and item_name = '$title' or item_name=''

result for above query:

Result:

SELECT usedBy,item_type,item_name,item_slot,item_rarity from descriptions where usedBy = '$hero' and item_type ='$type' or item_type != '' and item_rarity='$rarity' or item_rarity !='' and item_slot='$slot' or item_slot != '' and item_name = '$title' or item_name !=''

Above query shown all the records of the table

Result :

Thanks in advance.

Answer 1

Try use of % sign with Like For example:

SELECT usedBy,item_type,item_name,item_slot,item_rarity from descriptions where usedBy LIke '%$hero%' and item_type LIKE '%$type%' ;

Answer 2

You must build your WHERE condition dynamically and put only variable that are not empty :

// build a list of conditions based on filters data
$conditions= array();
if($filters['hero'] != '')
    $conditions[] = "usedBy = '" . $filters['hero'] . "'" ;
if($filters['type'] != '')
    $conditions[] = "type = '" . $filters['type'] . "'" ;
....

// build the SQL query
$query = "SELECT usedBy,item_type,item_name,item_slot,item_rarity from descriptions where " . implode(' AND ', $conditions) 

In this situation, make sure you validate and escape correctly your data to avoid SQL injections.