Understanding a PHP Generated JSON Array

Question

I'm trying to make sense of the JSON output and I was hoping someone here might be kind enough to walk me through it as it's been a while since I used JSON.

I have the following PHP

$Query01 = "SELECT `Department`,`DepartmentHeadID` FROM `Department`";
$Result01 = mysql_query($Query01) or die("Error 01: " . mysql_error());

while($r = mysql_fetch_array($Result01))
{

// Create JSON Data:
$rows[] = $r;
}
//  echo json_encode($rows);


$Data = json_encode($rows);
echo '<pre>';
print_r(json_decode($Data));
echo '</pre>';

Which generates the following:

Array
(
[0] => stdClass Object
    (
        [0] => Despatch
        [Department] => Despatch
        [1] => 1
        [DepartmentHeadID] => 1
    )

[1] => stdClass Object
    (
        [0] => Factory
        [Department] => Factory
        [1] => 2
        [DepartmentHeadID] => 2
    )

[2] => stdClass Object
    (
        [0] => Finishing
        [Department] => Finishing
        [1] => 3
        [DepartmentHeadID] => 3
    )

[3] => stdClass Object
    (
        [0] => Accounts
        [Department] => Accounts
        [1] => 8
        [DepartmentHeadID] => 8
    )

[4] => stdClass Object
    (
        [0] => Reps
        [Department] => Reps
        [1] => 13
        [DepartmentHeadID] => 13
    )

All I was expecting was the column Department & DepartmentHeadID

Would really appreciate understanding this output a little more.

Any thoughts...?

What you have got is the columns `Department` and `DepartmentHeadID` for each row returned by your SQL query.... you have each record as a Standard Class object, because that's the default for json_decode; use json_decode with true for the second argument, and those records will be an associative array instead — Mark Baker, Jun 13 '15 at 22:42

score 0 · Accepted Answer · edited May 23 '17 at 11:43

You actually missed that part in the documentation of array mysql_fetch_array ( resource $result [, int $result_type = MYSQL_BOTH ] )

result_type
The type of array that is to be fetched. It's a constant and can take the following values: MYSQL_ASSOC, MYSQL_NUM, and MYSQL_BOTH.

The type of returned array depends on how result_type is defined. By using MYSQL_BOTH (default), you'll get an array with both associative and number indices.

source : http://php.net/manual/en/function.mysql-fetch-array.php

Since MYSQL_BOTH is the default value for $result_type when you do not pass the second parameter to mysql_fetch_array, you end up with both the number and associative indices in your array.
So if you only want Department & DepartmentHeadID, you should go by

$r = mysql_fetch_array($Result01, MYSQL_ASSOC)

Using MYSQL_ASSOC, you only get associative indices (as mysql_fetch_assoc() works)

Bottom line : I would also recommend to prepare yourself to the deprecation of mysql_* functions as you can clearly see it stated in the official documentation linked here above and that you get information about PDO
A good starting point may be this question : Why shouldn't I use mysql_* functions in PHP?

Thanks @b.enoit.be It's been so long since I worked with JSON that I missed that and was banging my head against a wall sorting it out. I appreciate what you say about switching to PDO and would do that but for the fact that we are using an antiquated system and have to do things this way (FOR NOW). Thanks very much for your help. — Harlequin, Jun 14 '15 at 16:18

Understanding a PHP Generated JSON Array

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