使用下拉值查询mySQL数据库

Question

I've got below snippet where $filter_xx values are extracted from a dropdown basis user choice.

I'm trying to query the mySQL database with what the user chose to query the database with via dropdown selection.

You will see that there are 4 $filter_xx variables and how many of them are set in a given instance is completely random.

The issue is when I use && in the query it checks if all four parameters are true and then throws and output. (Well I know && is suppose to work that way!). I tried replacing all && operators with || and had no luck.

How do I search the database with only options selected by the user?

    if(isset($filter_brand) || isset($filter_year) || isset($filter_month) || isset($filter_status)) 
         {
          $query = "SELECT * FROM targets WHERE brand='$filter_brand' && startyear='$filter_year' && startmonth='$filter_month' && status='$filter_status' ORDER BY createdon DESC";
          } else {
          $query = "SELECT * FROM targets ORDER BY createdon DESC";
         }

Answer 1

Try By This

$join = "";
//TAKE ONE BLANK VARIBLE THAT JOIN IF VALUE IS SET

if(isset($filter_brand)){
    //IF VALUE ISSET THAN IT ADDED TO QUERY 
    $join .= " AND brand='$filter_brand'";
}

if(isset($filter_year){
    $join .= " AND startyear='$filter_year'";
}

$query = "SELECT * FROM targets WHERE id != '' $join ORDER BY createdon DESC";