Convert json array value to integer

Question

I am querying and returning a numeric column from a MySQL table to a json array. However, when I try to access the last element in the array, it returns it as a string. I tried casting it with an int, but then it returns a 0. Here is my code:

public function get_latest_subcategory_id() {

    $ids = $this->query("SELECT SubCategory_ID FROM SubCategory");
    if ($ids->num_rows > 0) {

        $arr_json = array();
        while ($row = $ids->fetch_row()) {
            $json = json_encode($row);
            $arr_json[] = $json;
        }
        echo $arr_json[$ids->num_rows-1];
    } else
        return null;
}

Is there a way I can retrieve it as an integer?

What is your final goal? You are encoding each query row before adding it to array. I think you have instead to create a standard array and to encode it at the end. — fusion3k
– fusion3k, Commented Apr 24, 2016 at 23:02
i just want to be able to get the entire numeric column (consists of IDs) from my table, and grab the last element (the most recent ID). — CircAnalyzer
– CircAnalyzer, Commented Apr 24, 2016 at 23:03
You are making an array of JSON objects though. If all you need is the the last ID then why does JSON need to be involved at all? — Chris
– Chris, Commented Apr 24, 2016 at 23:04

Chris · Accepted Answer · 2016-04-24 23:08:32Z

2

The JSON doesn't really do anything here. It's also really inefficient to go through the entire database just to get the last row. Why not do something like this?

public function get_latest_subcategory_id() {
    $ids = $this->query("SELECT SubCategory_ID FROM SubCategory ORDER BY SubCategory_ID DESC LIMIT 1");
    if ($ids->num_rows > 0) {
        $row = $ids->fetch_row();
        return intval($row[0]);
    } else
        return null;
}

answered Apr 24, 2016 at 23:08

Chris

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2 Comments

CircAnalyzer Over a year ago

Does this method not go through the entire database?

Chris Over a year ago

@DeeTee No, ORDER BY SubCategory_ID DESC tells MySQL to return the highest SubCategory_ID first and LIMIT 1 tells MySQL to only return the first result.

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