JSON encode MySQL results

Question

How do I use the json_encode() function with MySQL query results? Do I need to iterate through the rows or can I just apply it to the entire results object?

Answer 1

$sth = mysqli_query($conn, "SELECT ...");
$rows = array();
while($r = mysqli_fetch_assoc($sth)) {
    $rows[] = $r;
}
print json_encode($rows);

The function json_encode needs PHP >= 5.2 and the php-json package - as mentioned here

Modern PHP versions support mysqli_fetch_all() function that will get your array in one go

$result = mysqli_query($conn, "SELECT ...");
$rows = mysqli_fetch_all($result); // list arrays with values only in rows
// or
$rows = mysqli_fetch_all($result, MYSQLI_ASSOC); // assoc arrays in rows

print json_encode($rows);

Answer 2

If you need to put selected rows in a distinct element of returned json, you can do it like this: first, get the $rows array like in the accepted answer and then put it in another array like this

print json_encode(['object_name' => $rows]);

Answer 3

http://www.php.net/mysql_query says "mysql_query() returns a resource".

http://www.php.net/json_encode says it can encode any value "except a resource".

You need to iterate through and collect the database results in an array, then json_encode the array.

Answer 4

When using PDO

Use fetchAll() to fetch all rows as an associative array.

$stmt = $pdo->query('SELECT * FROM article');
$rows = $stmt->fetchAll(PDO::FETCH_ASSOC);
echo json_encode($rows);

When your SQL has parameters:

$stmt = $pdo->prepare('SELECT * FROM article WHERE id=?');
$stmt->execute([1]);
$rows = $stmt->fetchAll(PDO::FETCH_ASSOC);
echo json_encode($rows);

When you need to rekey the table you can use foreach loop and build the array manually.

$stmt = $pdo->prepare('SELECT * FROM article WHERE id=?');
$stmt->execute([1]);

$rows = [];
foreach ($stmt as $row) {
    $rows[] = [
        'newID' => $row['id'],
        'Description' => $row['text'],
    ];
}

echo json_encode($rows);

When using mysqli

Use fetch_all() to fetch all rows as an associative array.

$res = $mysqli->query('SELECT * FROM article');
$rows = $res->fetch_all(MYSQLI_ASSOC);
echo json_encode($rows);

When your SQL has parameters you need to perform prepare/bind/execute/get_result.

$id = 1;
$stmt = $mysqli->prepare('SELECT * FROM article WHERE id=?');
$stmt->bind_param('s', $id); // binding by reference. Only use variables, not literals
$stmt->execute();
$res = $stmt->get_result(); // returns mysqli_result same as mysqli::query()
$rows = $res->fetch_all(MYSQLI_ASSOC);
echo json_encode($rows);

When you need to rekey the table you can use foreach loop and build the array manually.

$stmt = $mysqli->prepare('SELECT * FROM article WHERE id=?');
$stmt->bind_param('s', $id);
$stmt->execute();
$res = $stmt->get_result();

$rows = [];
foreach ($res as $row) {
    $rows[] = [
        'newID' => $row['id'],
        'Description' => $row['text'],
    ];
}

echo json_encode($rows);

When using mysql_* API

Please, upgrade as soon as possible to a supported PHP version! Please take it seriously. If you need a solution using the old API, this is how it could be done:

$res = mysql_query("SELECT * FROM article");

$rows = [];
while ($row = mysql_fetch_assoc($res)) {
    $rows[] = $row;
}

echo json_encode($rows);

Answer 5

if ($result->num_rows > 0) {
    # code...
    $arr = [];
    $inc = 0;
    while ($row = $result->fetch_assoc()) {
        # code...
        $jsonArrayObject = (array('lat' => $row["lat"], 'lon' => $row["lon"], 'addr' => $row["address"]));
        $arr[$inc] = $jsonArrayObject;
        $inc++;
    }
    $json_array = json_encode($arr);
    echo $json_array;
} else {
    echo "0 results";
}

Answer 6

The above will not work, in my experience, before you name the root-element in the array to something, I have not been able to access anything in the final json before that.

$sth = mysql_query("SELECT ...");
$rows = array();
while($r = mysql_fetch_assoc($sth)) {
    $rows['root_name'] = $r;
}
print json_encode($rows);

That should do the trick!

Answer 7

The code below works fine here!

<?php

$con = mysqli_connect("localhost",$username,$password,"databaseName");

$query = "the query here";
$result = mysqli_query($con,$query);

$rows = array();
while($r = mysqli_fetch_array($result)) {
    $rows[] = $r;
}
echo json_encode($rows);

mysqli_close($con);

Answer 8

<?php

define('HOST', 'localhost');
define('USER', 'root');
define('PASS', '');
define('DB', 'dishant');

mysqli_report(MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT);
$con = mysqli_connect(HOST, USER, PASS, DB);

$sql = "select * from demo ";
$sth = mysqli_query($con, $sql);
$rows = array();
while ($r = mysqli_fetch_array($sth, MYSQLI_ASSOC)) {
    $row_array['id'] = $r;

    array_push($rows, $row_array);
}
echo json_encode($rows);

array_push($rows,$row_array); helps to build an array otherwise it gives the last value in the while loop.

This works like append method of StringBuilder in Java.

Answer 9

My simple fix to stop it putting speech marks around numeric values...

while($r = mysql_fetch_assoc($rs)){
    while($elm=each($r))
    {
        if(is_numeric($r[$elm["key"]])){
                    $r[$elm["key"]]=intval($r[$elm["key"]]);
        }
    }
    $rows[] = $r;
}   

Answer 10

Sorry, this is extremely long after the question, but:

$sql = 'SELECT CONCAT("[", GROUP_CONCAT(CONCAT("{username:'",username,"'"), CONCAT(",email:'",email),"'}")), "]") 
AS json 
FROM users;'
$msl = mysql_query($sql)
print($msl["json"]);

Just basically:

"SELECT" Select the rows    
"CONCAT" Returns the string that results from concatenating (joining) all the arguments
"GROUP_CONCAT" Returns a string with concatenated non-NULL value from a group

Answer 11

One more option using FOR loop:

 $sth = mysql_query("SELECT ...");
 for($rows = array(); $row = mysql_fetch_assoc($sth); $rows[] = $row);
 print json_encode($rows);

The only disadvantage is that loop for is slower then e.g. while or especially foreach

Answer 12

For example $result = mysql_query("SELECT * FROM userprofiles where NAME='TESTUSER' ");

1.) if $result is only one row.

$response = mysql_fetch_array($result);
echo json_encode($response);

2.) if $result is more than one row. You need to iterate the rows and save it to an array and return a json with array in it.

$rows = array();
if (mysql_num_rows($result) > 0) {
    while($r = mysql_fetch_assoc($result)) {
       $id = $r["USERID"];   //a column name (ex.ID) used to get a value of the single row at at time
       $rows[$id] = $r; //save the fetched row and add it to the array.
    }
}    
echo json_encode($rows);

Answer 13

I solved like this

$stmt->bind_result($cde,$v_off,$em_nm,$q_id,$v_m);
    $list=array();
    $i=0;
    while ($cresult=$stmt->fetch()){    


        $list[$i][0]=$cde;
        $list[$i][1]=$v_off;
        $list[$i][2]=$em_nm;
        $list[$i][3]=$q_id;
        $list[$i][4]=$v_m;
        $i=$i+1;
    }
    echo json_encode($list);        

This will be returned to ajax as result set and by using json parse in javascript part like this :

obj = JSON.parse(dataX);

Answer 14

We shouldn't see any use of mysql_ functions in modern applications, so either use mysqli_ or pdo functions.

Explicitly calling header("Content-type:application/json"); before outputting your data payload is considered to be best practice by some devs. This is usually not a requirement, but clarifies the format of the payload to whatever might be receiving it.

Assuming this is the only data being printed, it is safe to print the json string using exit() which will terminate the execution of the script as well. This, again, is not essential because echo will work just as well, but some devs consider it a good practice to explicitly terminate the script.

---

MySQLi single-row result set from query result set object:

exit(json_encode($result->fetch_assoc()));  // 1-dimensional / flat

MySQLi multi-row result set from query result set object:

Prior to PHP 8.1.0, available only with mysqlnd.

exit(json_encode($result->fetch_all(MYSQLI_ASSOC)));  // 2-dimensional / array of rows

MySQLi single-row result set from prepared statement:

$result = $stmt->get_result();
exit(json_encode($result->fetch_assoc()));  // 1-dimensional / flat

MySQLi multi-row result set from prepared statement:

$result = $stmt->get_result();
exit(json_encode($result->fetch_all(MYSQLI_ASSOC)));  // 2-dimensional / array of rows

PDO single-row result set from query result set object:

exit(json_encode($result->fetch(PDO::FETCH_ASSOC)));  // 1-dimensional / flat

PDO multi-row result set from query result set object:

exit(json_encode($result->fetchAll(PDO::FETCH_ASSOC)));  // 2-dimensional / array of rows

PDO single-row result set from prepared statement:

exit(json_encode($stmt->fetch(PDO::FETCH_ASSOC)));  // 1-dimensional / flat

PDO multi-row result set from prepared statement:

exit(json_encode($stmt->fetchAll(PDO::FETCH_ASSOC)));  // 2-dimensional / array of rows

---

Obey these rules to prevent the possibility of generating invalid json.:

1. you should only call json_encode() after you are completely finished manipulating your result array and
2. you should always use json_encode() to encode the payload (avoid the urge to manually craft a json string using other string functions or concatenation).

---

If you need to iterate your result set data to run php functions or provide functionality that your database language doesn't offer, then you can immediately iterate the result set object with foreach() and access values using array syntax -- e.g.

$response = [];
foreach ($result as $row) {
    $row['col1'] = someFunction($row['id']);
    $response[] = $row;
}
exit(json_encode($response));

---

If you are calling json_encode() on your data payload, then it won't make any difference to whether the payload is an array of arrays or an array of objects. The json string that is created will have identical syntax.

---

You do not need to explicitly close the database connection after you are finished with the connection. When your script terminates, the connection will be closed for you automatically.

Answer 15

we could simplify Paolo Bergantino answer like this

$sth = mysql_query("SELECT ...");
print json_encode(mysql_fetch_assoc($sth));