converting php array into a single JSON object - php

Question

I am having an issue with how I am converting my php array into a JSON object. No matter what I try, I either print everything out as multiple objects or it comes out as null.Wrapping it in pre tags, here is the closest that I got it:
My code:
$content = mysqli_query($dbcon,
"SELECT title, last_name AS lastname
FROM revision, field_last_name
WHERE vid = entity_id;"
);
echo "<pre>";
while($row = mysqli_fetch_array($content))
{
print json_encode($row);
print '<br/>';
}
echo "</pre>";
My output:
{"0":"John Apple","title":"John Apple","1":"Apple","lastname":"Apple"}
{"0":"Kumar Patel","title":"Kumar Patel","1":"Patel","lastname":"Patel"}
{"0":"Michaela Quinn","title":"Michaela Quinn","1":"Quinn","lastname":"Quinn"}
{"0":"Peyton Manning","title":"Peyton Manning, MD","1":"Manning","lastname":"Manning"}
{"0":"John Doe","title":"John Doe","1":"Doe","lastname":"Doe"}
{"0":"Jane Lee","title":"Jane Lee","1":"Lee","lastname":"Lee"}
{"0":"Dan McMan","title":"Dan McMan","1":"McMan","lastname":"McMan"}
{"0":"Yu Win","title":"Yu Win","1":"Win","lastname":"Win"}
My two questions are:
1) Why is there a "0":"John Apple" and a "1":"Apple" when all I want is "title":"John Apple" and "lastname":"Apple" in my object?
2) Why is everything displaying as multiple objects?
Thanks!
---EDIT---
$arr = array()
echo "<pre>";
while($row = mysqli_fetch_assoc($content))
{
$arr[] = $row;
}
print $arr;
echo "</pre>";

Answer 1

field_last_name is your table name? can you distinguish each column name prefix by table name like revision.title in your query and get all data in a single array and then json_encode it?
$content = mysqli_query($dbcon,
"SELECT title, last_name AS lastname
FROM revision, field_last_name
WHERE vid = entity_id;"
);
$arr = array();
echo "<pre>";
while($row = mysqli_fetch_assoc($content))
{
$arr[] = $row;
}
print_r(json_encode($arr));
echo "</pre>";

Answer 2

Change this:
while($row = mysqli_fetch_array($content))
{
print json_encode($row);
print '<br/>';
}
To this:
$row = mysqli_fetch_assoc($content);
json_encode($row);

Answer 3

...because you're printing out multiple objects. If you want a single object which is an array, you need to append the results of mysql_fetch_assoc (see other answer covering field names vs positions) to an array, then json_encode the array in one shot. Example:
$myarray = array();
while($row = mysqli_fetch_assoc($content))
{
$myarray[] = $row;
print '<br/>';
}
print json_encode($myarray);